ASGN (ASGN) 8-K Regulation FD Disclosure

Exhibit 99.1

Acquisition of Apex Systems, Inc.
March 20, 2012

Peter Dameris

President & CEO

Jim Brill

CFO

Rand Blazer

COO, Apex Systems

Ted Hanson

CFO, Apex Systems

Mike McGowan

President, Oxford

2

Safe Harbor

Certain statements made in this presentation should be considered
forward-looking statements as defined in the Private Securities Litigation
Reform Act of 1995. These include statements about our future results of
operations and operating targets, the size of the markets in which we
operate, and our efforts to increase our market share and revitalize our
business. We caution investors that these forward-looking statements are
not guarantees of future performance, and actual results may differ
materially. Investors should consider the important risks and uncertainties
that may cause actual results to differ, including those discussed in our
annual report on Form 10-K for the year ended December 31, 2011 and
other filings we make with the Securities and Exchange Commission. We
assume no obligation to update this presentation, which speaks as of
today's date.

3

Transaction Overview

On Assignment to acquire Apex Systems, a leading information technology and
workforce solutions firm, for $600 million in cash and stock

–Cash consideration of $383 million

–On Assignment has secured committed financing for $540 million of credit facilities, consisting of a
$50 million revolving credit facility (undrawn at close) and a $490 million term loan

–Existing On Assignment and Apex Systems debt to be refinanced as part of the transaction

–Estimated funded debt at close:3.75x pro forma 3/31/12E LTM Adjusted EBITDA ¹ (excluding any
potential synergies)

–Stock consideration of $217 million

–Stock consideration based on an ASGN share price of $13.79, subject to collar

–Based on a fixed price collar of +/- 10%, a maximum of 17.5 million and a minimum of 14.3 million
new ASGN shares will be issued to Apex Systems shareholders at transaction close

–Structured as a merger with a Section 338(h)(10) election, resulting in significant cash tax savings
(estimated to be approximately $14 million per year for 15 years)

–Apex Systems will operate as a division of On Assignment

–Transaction is expected to close in Q2 2012

–Standard closing conditions including HSR approval and On Assignment shareholder approval

Note:

1 Excludes transaction costs and certain non-material and non-recurring expenses

4

Transaction Highlights

Ease of Integration

•Immediately becomes the second largest IT staffing provider in the U.S. with approximately
$1 billion of revenue from IT staffing in 2011 (represents ~75% of total pro forma combined
revenue of $1.3 billion)

•Uniquely positioned in the marketplace as the only company providing a “full spectrum” of IT
staffing solutions from high-end to mission-critical assignments

•Benefit from strong secular trend in IT staffing

•Expected industry growth of 12% in 2012

Apex & Oxford:
A Powerful
Combination in
IT Staffing

•Expected to be immediately accretive on both a GAAP and cash EPS basis

•The combined company benefits from the 338(h)(10) election, resulting in approximately $14
million of annual cash tax savings over 15 years

•Increased scale along with strong revenue and free cash flow generation results in rapid
deleveraging

Attractive Financial
Characteristics

•On Assignment is bolstered by Apex Systems’ senior management team and its impressive
track record of consistent revenue growth and industry leading margins

•Veteran cadre of seasoned industry professionals

Experienced
Management Team

Increased Scale in
an Attractive
Market

•The On Assignment and Apex Systems combination creates one of the largest, fastest growing
and most profitable professional staffing companies in the U.S.

•Transaction accretion excludes any potential synergy savings

•Pro forma combined 2011 revenue of $1.3 billion

4

•Seamless integration given that Apex and Oxford do not compete against one another

•Oxford specializes in high-end IT skills and Apex focuses on mission critical IT skills

•Minimal overlap in existing customer bases

•On Assignment has a proven track record of successful platform acquisitions

5

Transaction Rationale

Highly Complementary Acquisition

•Focused on different sets of IT skills

•No channel conflicts

•Limited integration required

•Similar business models and corporate cultures

Diversifies Revenues

•Broaden services offering across IT skills

•Vertical and geographical diversification

•Improve penetration into new customers

•Increases ability to expand customer base in the
Healthcare vertical

•Expand permanent placement business

•Significant cross-selling opportunities

•Diversifies Apex revenue stream beyond IT
staffing

Strong Financial Profile

•Accretive to revenue growth and earnings

•Strong conversion of EBITDA to cash flow

•Significant cash tax savings, resulting in rapid
debt paydown

Potential Synergies

•Leverage highly scalable back-office infrastructure

•Consolidation of billing and payroll

•Leverage expertise in sales and recruiting

6

•Integration will be seamless to employees,
contract professionals and customers

•Senior management of both On Assignment
and Apex remain in place and ultimately
report to CEO Peter Dameris

•No major changes to recruitment and sales
models and commission plans

•No channel conflicts

Merger Integration

7

Apex & Oxford: A Powerful Combination in IT Staffing

IT

Overview

Selected

Positions

Average

Bill Rate

Contract
Professional /
Employees

+

Other

•Mission critical IT staffing that
Fortune 1000 and mid-market
companies require to run daily
operations

•Network Engineers

•Application Developers

•Social & Mobile App. Developers

•Help Desk

•$60 per hour

•Qualified Database: 400,000+

•Currently on assignment:
~16,500

•Full-time employees: ~1,100

•Deep industry knowledge and
relationship with clients

•Sales-driven culture

•Offers full spectrum of IT
staffing services from high-end
special projects to mission
critical daily operations

•Flexible staffing services to
meet clients’ needs

•Full spectrum of IT skills

•Bill rates and skill set
appropriate for high-end and
everyday IT projects

•Estimated combined average
bill rate of ~$75 per hour

=

•Diverse database of talent to
meet all IT needs

•Powerful combination of well-
respected, fast-growing IT
staffing firms

IT / Engineering

•High-end IT and engineering
staffing that require hard-to-
find skills

•Programmers

•Database Designers

•Enterprise Software Developers

•$116 per hour1

•Qualified Database: 35,000+

•Currently on assignment:
~1,400

•Full-time employees: ~590

•Unsurpassed recruiting
capability to fulfill coveted, high
-end and scarce skill set

7

1 Q4 2011 Average

8

A Focus on Information Technology

Forecasted IT staffing revenues to be $22.7 billion in 20121

Growth Characteristics

•IT segment is estimated to grow by 13% in 2011 and
12% in 20121

($ in billions)

Projected Market Size1

-IT staffing involves providing temporary professionals and placing full-time employees in areas ranging
from multiple platform systems integration to end-user support, including specialists in programming,
networking systems integration, database design and help desk support.

Source:

1 Staffing Industry Analysts Insight: Staffing Industry Forecast (September 2011)

Industry

Potential

Shortage of

Talent

•IT has recovered quicker than most
other staffing segments; and is the
only professional staffing segment
expected to surpass 2008 levels in
the current year

•Growth in 2012 is expected to be
driven by demand in the healthcare
industry, given deadlines for
conversions implemented by the US
Dept. of Health & Human Services

•One of the main constraints on
growth in this segment is a shortage
of talent, and not necessarily
demand, due to the exodus of many
mid-career professionals following
the tech bubble and a steady
decline in new computer science
graduates

9

Pro Forma Business Diversification

LIFE SCIENCES

$155.3 million

HEALTHCARE STAFFING

$94.6 million

PHYSICIAN STAFFING

$80.6 million

IT AND ENGINEERING (OXFORD)

$266.7 million

APEX SYSTEMS

$705.2 million

2011 Revenue

Pro Forma 2011 Revenue Mix

Pro Forma 2011 Revenue: $1.3 billion

IT and Engineering staffing represents ~75% of pro forma revenue

10

Pro Forma Combined Summary Financials

10

Excludes all transaction adjustments and potential synergies

Note:

1 Pro forma income statement will be included in the proxy statement to be filed by On Assignment with the SEC

2 Adjusted EBITDA adds back stock-based compensation, acquisition related expenses and non-recurring expenses

2009A - 2012E Pro Forma Combined Company Financials

11

11

Pro Forma Cash Flow Generation

Cumulative FCF
Generated

$285 Million

Note: Chart dollars are in thousands

1 Free cash flow is defined as cash flow from operations less capital expenditures

Since 2007, On Assignment and Apex combined have generated
$285 million in Free Cash Flow from operations1

Both organizations have exhibited strong cash flow
generation, even through the financial crisis, and have the
ability to rapidly deleverage

12

•Apex has capitalized on the
secular shift within IT Staffing

•One of the fastest growing
staffing firms in North America

•Over 1,200 clients (mostly
Fortune 1000) with a presence in
49 markets

•Over 16,000 temporary IT
professionals staffed annually

Note: Shaded regions indicate recessionary periods

($ in Millions)

Source: Staffing Industry Analysts

Apex Systems Overview

Largest IT Staffing firms in the U.S.

Strong Revenue Growth

13

National Presence with Scale

Apex currently operates in 43 out of SIA’s Top 50 Markets

High Operating Leverage and Infrastructure to Support a Much Larger Company

13

900+ Sales & Recruiting
Staff

190+ Support Staff

1.4 million+ Candidates

National Training Center

1,200+ Clients

100+ National Accounts

6,000+ IT Professionals on
Billing with Clients Each
Week and Rapidly Growing

14

Enviable, Blue Chip Client Base Across All Industries

Information
Technology

Business
Services

Financials

Healthcare /
Pharma

Government
Services

Consumer
Industrials

Telecommunications

14

§Outsourced
Services

§Data Processing

§Computers

§Peripherals

§Hardware

§Software

§Semiconductors

§Internet

§Banks

§Insurance

§Capital Markets

§Commercial
Banking

§Mortgage

§REIT

§Biotechnology

§Life Sciences

§Health
Technology

§Suppliers

§Equipment

§Government
Activities

§Aerospace /
Defense

§Compressus

§Government
Contractor

§Food

§Retail

§Auto

§Hotels

§Machinery

§Professional
Services

§Construction

§Engineering

§Utilities

§Energy

§Wireless

§Wireline

§Media

§Cable

§Communications
Equipment

15

Rand Blazer

•Former CEO of Bearing Point

•Grew KPMG Consulting/Bearing Point from $700 million
to $3.4 billion in 7 years

•Former President and GM of SAP Public Services, Inc.

Ted Hanson

•13 year tenure with Apex Systems

•Former Virginia CFO of the Year

•Former CFO of a telecommunications firm

Strong Second Tier Management

•7 EVPs whose average tenure with Apex is 13 years

•52 Principals who have contributed significantly to the performance of Apex with an average
tenure at Apex of 10 years

Proven Leadership Team

16

Source: Company management

Note: Shaded regions indicate recessionary periods

1 LTM as of January 2012

Strong Financial Performance

•One of the fastest growing pure play IT firms in the
U.S.

•Proven ability to perform well through economic
uncertainty

•Industry leading profit margins

•Large scale firm with potential to realize significant
operating leverage

Revenue

$ in Millions

EBITDA & EBITDA Margin

Gross Profit & Margin

$ in Millions

16

1

1

1

17

Source: Wall Street research, Staffing Industry Analysts (SIA) and company filings

Note: Shaded regions indicated recessionary periods and LTM as of January 2012

1 Revenue growth represents SIA’s staffing industry growth

2 Industry margin represents average EBITDA margins for ADEN, ASGN, KFRC, MAN, and RAND

Track Record of Outperforming the Competition

•Singular focus on IT staffing which benefits from
favorable secular and sector trends

•National presence and robust infrastructure leading
to high operating leverage

•People-centric culture and sales-driven organization

•Best-in-class leadership

EBITDA & EBITDA Margin

EBITDA Margin 2

Revenue Growth 1

17

18

Additional Information and Where to Find It

In connection with the transaction, On Assignment will prepare a proxy statement to be filed with the SEC. When
completed, a definitive proxy statement and a form of proxy will be mailed to the shareholders of the Company. BEFORE
MAKING ANY VOTING DECISION, ON ASSIGNMENT’S SHAREHOLDERS ARE URGED TO READ THE PROXY
STATEMENT REGARDING THE TRANSACTION CAREFULLY AND IN ITS ENTIRETY BECAUSE IT WILL CONTAIN
IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION. On Assignment’s shareholders will be able to
obtain, without charge, a copy of the proxy statement (when available) and other relevant documents filed with the SEC
from the SEC’s website at http://www.sec.gov. On Assignment’s shareholders will also be able to obtain, without charge, a
copy of the proxy statement and other relevant documents (when available) by directing a request by mail or telephone to
On Assignment, Inc., Attn: Investor Relations, 36745 Malibu Hills Road, Calabasas, California 91301, telephone: (818)
878-3136, or from the investor relations section of the company’s website, http://www.onassignment.com.

On Assignment, Apex Systems and their respective directors and executive officers and other persons may be deemed to
be participants in the solicitation of proxies in respect of the transaction. Information regarding On Assignment’s directors
and executive officers is available in On Assignment’s notice of annual meeting and proxy statement for its most recent
annual meeting and On Assignment’s Annual Report on Form 10-K for the year ended December 31, 2011, which were
filed with the SEC on April 27, 2011 and March 14, 2012, respectively. Other information regarding the participants in the
solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the
proxy statement and other relevant materials to be filed with the SEC.