Our Annual Meeting will be held at Sterling McCall Lexus, 10025 Southwest Freeway, Houston, TX 77074, on Wednesday, May 18, 2016,12, 2017, at 10:00 a.m., Central Daylight Time, or at such other time and place to which the meeting may be adjourned.

The proxy materials, including this proxy statement, the Notice of Annual Meeting, the Notice of Internet Availability, a proxy card, and our Annual Report to Stockholders on Form10-Kfor the fiscal year ended December 31, 20152016 are being distributed and made available to stockholders on or about April 8, 2016.

In accordance with rules approved by the Securities and Exchange Commission (“SEC”), beginning on or about April 8, 2016, we mailed the Notice of Internet Availability to certain beneficial owners of our common stock and stockholders of record containing instructions on how to access the proxy materials and vote online. In addition, the proxy materials were mailed to certain beneficial owners of our common stock and stockholders of record on or about April 8, 2016.10, 2017.

At our Annual Meeting, stockholders will act upon the matters outlined in the notice of meeting, including the election of eightnine director nominees, the advisory vote to approve executive compensation, advisory vote to approve the frequency of executive compensation advisory votes, the ratification of Ernst & Young LLP as

Only our stockholders as of 5:00 p.m., Central Daylight Time, on March 21, 201615, 2017 (the record date) are entitled to receive notice of the Annual Meeting and to vote at

You are entitled to one vote for each share of Group 1 common stock you owned at 5:00 p.m., Central

If your shares are registered directly in your name with our registrar and transfer agent, American Stock Transfer & Trust Company, LLC, you are considered a stockholder of record with respect to those shares.

If your shares are held in a brokerage account or by a bank or other nominee, you are considered the

If you are a stockholder of record on the record date, you may vote in person at the Annual Meeting or by proxy using any of the following methods:

Internet — visit the website shown on the proxy card (www.proxyvote.com) and follow the instructions at that website at any time prior to 11:59 p.m., Eastern Daylight Time, on May 17, 2016;

Telephone — within the U.S. or Canada, call thetoll-free telephone number shown on the proxy card and follow the instructions at any time prior to 11:59 p.m., Eastern Daylight Time, on May 17, 2016; or

Mail — if you receive a paper copy of the proxy materials, complete, sign and date the proxy card and return the proxy card in the prepaid envelope. Your proxy card must be received by the Company before the voting polls

If you vote by Internetinternet or telephone, do not return your proxy card. The telephone and Internetinternet voting

If you are a stockholder of record on the record date, you can revoke your proxy prior to the completion of voting at the Annual Meeting by:

If you are a street name stockholder you must follow the instructions of your broker, bank or other nominee to revoke your voting instructions. You may also vote in

If you hold your shares in “street name,” you will receive instructions from your broker, bank or other nominee describing how to vote your shares. If you do not instruct your broker, bank or other nominee how to vote your shares, they may vote your shares as they decide as to each routine matter under the rules of the New York Stock Exchange. Only Proposal No. 4 is considered a “routine” matter.

If you do not provide specific voting instructions to your broker onnon-routine matters, your broker may not cast a vote on the proposal, resulting in a brokernon-vote. Although any broker

The Company’s majority votingdirector resignation policy requires any director nominee in an uncontested election who receives a greater number of votes “withheld”“against” than votes “for” his or her election to tender his or her resignation promptly following the certification of the election results. The Nominating/Governance Committee of the Board will consider all of the relevant facts and circumstances and make a recommendation to the Board with respect to whether to accept the resignation. Within 90 days, the Board is required to take action with respect to the recommendation and to promptly disclose its decision. The majority votingdirector resignation policy is more fully described in “Information about Our

shares voted by duly submitting a proxy by mail, telephone or Internet,internet, unless the stockholder appropriately specifies otherwise, the management

Our Board of Directors recommends that you vote your shares “FOR” each of the director nominees; “FOR” the approval, on anon-binding advisory basis, of our executive compensation; for “ONE YEAR” for the

We need a quorum with respect to each proposal being submitted for stockholder vote. A quorum will be present for purposes of proposals 1, 2, 3, and 3,4, if the holders of a majority of the shares of common stock entitled to vote are present in person or represented by proxy at the Annual Meeting. Our independent inspector of election, Broadridge Financial Solutions will determine whether or not a quorum is present. There must be a quorum for the Annual Meeting to be held. Proxies received but marked as abstentions or brokernon-votes will be included in the calculation of votes considered to be present at the Annual Meeting.

We have engaged Alliance Advisors to assist with the solicitation of proxies for a fee not to exceed $5,000, plus reimbursement for reasonableout-of-pocket expenses. We will bear all expenses of soliciting proxies. We may reimburse brokerage firms, custodians, nominees, fiduciaries and other persons representing beneficial owners of our common stock for their reasonable

We have engaged Broadridge Financial Solutions to tabulate the votes and to serve as inspector of election at the Annual Meeting for a fee of approximately $3,500. Broadridge will separately tabulate For,

You may submit proposals for consideration at future stockholder meetings, including director nominations. Please read “Stockholder Proposals for 20172018 Annual

In 2015,2016, the Board held 10six meetings and acted by unanimous written consent twice.six times. Committees of the Board held a combined total of 21 meetings. Each incumbent director attended 91%95% or more of the aggregate of all meetings of the Board and the committees on which he or she served during the periods in which he or she served during fiscal 2015,2016, and, except for one director who was unable to attend one BoardCompensation Committee meeting, and one director who was unable to attend two committee meetings, attendance at such meetings was 100% for all directors then currently serving. Under our Corporate Governance Guidelines,

We are committed to good corporate governance which includes the highest standards of professional and personal conduct. Our Board has adopted several governance documents to guide the operation and direction of our Board and its committees, which include our Corporate Governance Guidelines, Code of Ethics, Code of Conduct and charters for the Audit Committee, Compensation Committee,

The Nominating/Governance Committee’s charter provides that the committee will annually assess the leadership structure of the Board and recommend a structure to the Board for approval. In 2015,2016, the Nominating/Governance Committee conducted that assessment, and determined that having an independent director serve asnon-executive Chairman of the Board continues to be in the best interest of our stockholders at this time. Our Chief Executive Officer is responsible for setting our strategic direction and providingday-to-day leadership, while the Chairman of the Board

Our Nominating/Governance Committee is responsible for identifying and recommending to our Board

that have a demonstrated record of integrity, sound business judgment, leadership, objectivity, independence of mind, and commitment. In selecting potential Board candidates, our Board seeks independent directors who represent a mix of

The Board has analyzed the independence of each director. It has affirmatively determined that Ms.Mses. Barth and Wright and Messrs. Adams, Arnold, Quinn, Strange, Szews and Watson (all of ournon-employee directors) are independent directors under the New York Stock Exchange’s listing standards. As part of its analysis, the Board determined that none of these directors has a material

We have in the past, and may, in the future, make donations to various charitable organizations. From time to time, some of our directors, officers and employees have been, and in the future may be,

Under our majority votingdirector resignation policy, in an uncontested election of directors, any nominee who receives a greater number of votes “withheld”“against” than votes “for” his or her election will, promptly following the certification of the stockholder vote, tender his or her written resignation to the Board for consideration by the Nominating/Governance Committee. The Nominating/Governance Committee will consider the resignation and will make a recommendation to the Board concerning whether to accept or reject it.

In determining its recommendation to the Board, the Nominating/Governance Committee will consider all factors it considers relevant, which may include:

The independent directors meet in executive session at each regularly scheduled meeting of our Board. Mr. Adams, ournon-executive Chairman of the Board,

Our Board, as a whole and through its committees, has broad responsibility for the oversight of risk management as well as specific risk management accountability for governance, overallwith a focus on the most significant risks facing the Company, including strategic, operational, risk, executive compensation, Chief Executive Officer succession planningfinancial and our system of internal controls, including financial reporting.legal and compliance risk. In its risk management role, our Board has the responsibility to satisfy itself that our risk management processes and controlssystems that have been put in place to identify and manage risks are adequatereasonable and functioning as designeddesigned. Our Board also has specific risk management accountability for governance, executive compensation and that our business is conducted wisely and in compliance with proper governance and applicable laws and regulations.Chief Executive Officer succession planning.

Much of our Board’s oversight work is delegated to various committees, which meet regularly and report back to the full Board. All committees have significant roles in carrying out the risk oversight and management function. Each committee is comprised entirely of independent directors, except the Finance/Risk Management Committee, and is responsible for overseeing risks associated with its respective area of responsibility as further detailed below.

The Finance/Risk Management Committee is charged with oversight of our risk exposure related to our operations, including, among other things, cyber security and data protection and litigation management, enterprise risk management strategies, strategies for our insurance programs and our compliance with covenants of material debt instruments. The Finance/Risk Management Committee monitors ourfinance-related activities and provides guidance to management and the Board concerning ourlong-range financial policies and objectives.

The Audit Committee is responsible for oversight of Company risks relating to accounting matters, financial reporting (primarily internal control risks) and legal and regulatory compliance. In fulfilling these oversight responsibilities, the Audit Committee meets with our management and independent registered public accounting firm regarding the adequacy of our financial controls and our compliance with legal, tax and regulatory matters, as well as our significant financial and accounting policies. The Audit Committee also separately meets with our director of internal audit on a regular basis, and with other members of management, as deemed appropriate, to review, among other things, the identified risk areas and scope of the internal audit approach. The Audit Committee receives regular reports regarding the status and findings of audits being conducted by the internal auditors and independent registered public accounting

to review adherence to policies and procedures, which are supported by a separate internal audit department.

Pursuant to its charter, the purposes and responsibilities of our Audit Committee are to:

In addition to, and in connection with, the purposes and responsibilities described above, the Audit Committee is directly responsible for the appointment, compensation, retention and oversight of the work of our independent registered public accounting firm. The

Pursuant to its charter, the purposes and responsibilities of our Compensation Committee are to:

matters relating to our Chief Executive Officer. In the case of our Chief

In February 2016,2017, the Compensation Committee considered the independence of PM&P in light of SEC rules and listing standards of the NYSE. The Compensation Committee requested and received a letter from PM&P addressing the consulting firm’s independence, including the following factors: (1) other services provided to us by the consultant; (2) fees paid by us as a percentage of the consulting firm’s total revenue; (3) policies or procedures maintained by the consulting firm that are designed to prevent a conflict of interest; (4) any business or personal relationships between the individual consultants involved in the engagement and a member of the Compensation Committee; (5) any company stock owned by the individual consultants involved in the engagement; and (6) any business or personal relationships between our executive officers and the consulting firm or the individual consultants involved in the engagement. The letter highlighted three additional factors that supported their independence: (1) PM&P has regular discussions with only the Compensation Committee (or select members of the Compensation Committee) present and where PM&P interacts with management, it is at the

Pursuant to its charter, the purposes and responsibilities of our Nominating/Governance Committee are to:

In connection with these purposes, the Nominating/Governance Committee actively seeks

The Nominating/Governance Committee may consider candidates for our Board from any reasonable source, including from a search firm engaged by the Nominating/Governance Committee or stockholder recommendations, provided that the procedures set forth below are followed. The Nominating/Governance Committee does not intend to alter the manner in which it evaluates candidates based on whether the candidate is recommended by a stockholder or not. However, in evaluating a candidate’s relevant business experience, the Nominating/Governance Committee may consider previous experience as a member of our Board. Any invitation to join our Board must be extended by our Board as a whole, by the Chairman of the Nominating/Governance Committee and by the Chairman of the Board.

Stockholders or a group of stockholders may recommend potential candidates for consideration by the Nominating/Governance Committee. For additional information on such requests and the applicable timing, please see “Stockholder Proposals for 20172018 Annual Meeting.”

In addition to the purposes described above, our Board has entrusted the Nominating/Governance Committee

Pursuant to its charter, the purposes of our Finance/Risk Management Committee are to:

At the request of the Finance/Risk Management Committee, management developed and presented to

At our 2015 Annual Meeting of Stockholders, we asked our stockholders to approve our Amended and Restated Certificate of Incorporation (“Restated Certificate”) and Second Amended and Restated Bylaws (“Bylaws”), which, among other things, declassified our Board of Directors. Our Restated Certificate and Bylaws currently provide for annual elections of directors.

Our Board of Directors has nominated eightnine directors for election at this Annual Meeting to hold office until the next annual meeting and the election of their

We have no reason to believe that any of the nominees will be unable or unwilling for good cause to serve if elected. However, if any nominee should become unable for any reason or unwilling for good cause to serve, proxies may be voted for another person nominated as a substitute by the Board, or the Board may reduce the number of directors.

The number of directors on our Board is reviewed annually and fixed by our Board from time to time. In February 2013,November 2016, the Board approved the number of directors serving on the Board to be eightnine members, and in February 2017, the Board expanded the number of directors serving on the Board to ten members. The Board will continue to evaluate the size of the Board and make adjustments as needed to meet the current and future needs of the Company.

Stockholders may not cumulate their votes in the election of our directors. Under Delaware law and our Bylaws, a pluralitymajority of the votes cast by stockholders entitled to vote in the election of directors, is required

Our Board believes that each of our directors is highly qualified to serve as a member of our Board. Each of our directors has contributed to the mix of skills, core competencies and qualifications of our Board. Our directors are highly educated and have diverse backgrounds and talents and extensive track records of success in what we believe are highly relevant positions with some of the most reputable organizations in the world. Our Board has also considered the fact that all of our directors have worked for, or served on the boards of directors of, a variety of companies in a wide range of industries. Many of our directors also have served as directors of Group 1 for many years and

Pursuant to Section 14A of the Exchange Act, our stockholders are entitled to cast a vote at the Annual Meeting to approve, on anon-binding advisory basis, the compensation of our Named Executive Officers,named executive officers, as disclosed in this proxy statement. As an advisory vote, Proposal 2 is not binding on our Board or its Compensation Committee, will not overrule any previous decisions made by our Board or its Compensation Committee, or require our Board or its Compensation Committee to take any future or remedial action. Although the vote isnon-binding, the Compensation Committee will take into account the outcome of the vote when considering future executive compensation decisions.

Our Board recognizes that executive compensation is an important matter for our stockholders. As described in detail in the CD&A section of this proxy statement, the Compensation Committee is tasked with the implementation of our executive compensation philosophy. The core of that philosophy has been and continues to be to pay our executive officers compensation that is competitive with amounts paid by our peer companies based on individual and Company performance. In particular, the Compensation Committee strives to attract, retain and motivate talented executives, to reward past performance measured against established goals and provide incentives for future performance, and to align executives’long-term interests with the interests of our stockholders. To do so, the Compensation Committee uses a combination ofshort- andlong-term incentive compensation to rewardnear-term performance and to encourage our executives’ commitment to ourlong-range, strategic business goals. It is always the intention of the Compensation Committee that our executive officers be compensated competitively and in a manner that is consistent with our strategy, sound corporate governance principles, and stockholder interests and concerns. Our Board believes that our compensation policies and practices are effective in achieving our Company’s goals of rewarding sustained financial and operating performance, leadership excellence and aligning the executives’long-term interests with those of our stockholders.

Every six years, we are required to conduct a nonbinding stockholder advisory vote on the frequency of futuresay-on-pay votes. At our 2011 Annual Meeting of Stockholders, our stockholders cast the highest number of votes for annualsay-on-pay votes. In light of this result and other factors considered by our Board, we have since held suchsay-on-pay votes on an annual basis. As six years have passed, this Proposal 3 provides our stockholders with a second opportunity at the Annual Meeting to cast a nonbinding advisory vote on how often we should conduct asay-on-pay vote at future annual meetings of stockholders.

The Board believes that continuing to conductsay-on-pay votesevery year(as opposed to every two years or three years) is appropriate for us. We believe that an annual advisory vote on executive compensation is the most appropriate option for us because it will allow our stockholders to provide more frequent, direct input on our compensation policies and practices, and the resulting compensation for our named executive officers. Stockholders will have the opportunity to consider our most recent compensation decisions and focus on increasing long-term stockholder value, and to give immediate and direct feedback on our executive compensation programs. The Board also believes an annual advisory stockholder vote promotes corporate transparency

The Audit Committee has appointed Ernst & Young, LLP (“Ernst & Young”) as the independent registered public accounting firm of Group 1 for the fiscal year ending December 31, 2016.2017. We have been advised by Ernst & Young that the firm has no relationship with Group 1 or its subsidiaries other than

The increase in the 2015 Tax Fees, reflected in the table on the preceding page, is related principally to tax planning and advice related to acquisitions in the UK and the restructuring of the Company’s UK operations.

The Audit Committee considers whether the provision of these services is compatible with maintaining Ernst & Young’s independence, and has determined such services for fiscal 20142015 and 20152016 were compatible. All of the services described above werepre-approved by the Audit Committee pursuant to paragraph (c)(7)(ii)(C) ofRule 2-01 ofRegulation S-X under the Exchange Act, to the extent that rule was applicable during fiscal 20142015 and 2015.2016.

The Audit Committee has established a policy requiringpre-approval by the Audit Committee of all services (audit andnon-audit) to be provided to us by our independent registered public accounting firm. In accordance with this policy, the Audit Committee has given its annual approval for the provision of audit services by Ernst & Young, and has also given its approval for up to a year in advance for the provision by Ernst & Young of particular categories or types ofaudit-related, tax and permittednon-audit services, in each case subject to a specific budget.

Any proposed services to be provided by the independent registered public accounting firm not

This Compensation Discussion and Analysis provides a detailed description of our executive compensation philosophy and programs, the compensation decisions the Compensation Committee has made under those programs and the factors considered in making those decisions. As discussed in greater detail below, our compensation plans are designed to reward our Named Executive Officersnamed executive officers for the achievement of these results for our Company and our stockholders. The Compensation Discussion and Analysis focuses on the compensation of our Named Executive Officersnamed executive officers as of December 31, 2015,2016, who were:

In 2015,2016, Group 1 continued to deliver record setting financial results and increased operational effectiveness. Our results included:

The Committee continuously reviews best practices in executive compensation and has made several adjustments to elements of our compensation programs over the past several years to further align

Our Board has entrusted the Committee with overall responsibility for establishing, implementing and monitoring our executive compensation program. Our Chief Executive Officer and Senior Vice President of Human Resources, Training and Operations Support, also play a role in the implementation of the executive compensation process, by overseeing the performance and dynamics of the executive team and generally keeping the Committee informed. All final decisions regarding our Named Executive Officers’named executive officers’ compensation remain with the Committee, except in the case of our Chief Executive Officer where the independent members of the Board makesmake all decisions with the benefit of recommendations from the Committee.

The Committee has historically engaged Pearl Meyer & Partners (“PM&P”), an executive compensation firm, to serve as its compensation consultant and to advise on