Exhibit 21.1
SUBSIDIARIES OF ABM INDUSTRIES INCORPORATED
The following is a list of subsidiaries of the company as of October 31, 2018, omitting subsidiaries which, considered in the aggregate, would not constitute a significant subsidiary.
| Company | Where Incorporated or Organized | |
| ABM INDUSTRIES INCORPORATED | Delaware | |
| (*) | ABM Aviation, Inc. | Georgia |
| Omni Serv Limited | England | |
| Air Serv Middle East Hospitality Services LLC | UAE | |
| OFJ Connections | England | |
| OFJ Airlinks Limited | England | |
| ABM International (Holdings) B.V. | Holland | |
| IFM Capital Ltd. | Bermuda | |
| ABM Group UK Limited | England | |
| ABM Facility Services UK Limited | England | |
| ABM Facility Services Scotland Limited | England | |
| Eclipse Contract Cleaning Limited | Scotland | |
| GBM Services (Civic) Limited | England | |
| BRBIBR Limited | England | |
| ABM Critical Solutions Limited | England | |
| Westway Services Holdings (2014) Ltd. | England | |
| Westway Services Holdings (2010) Ltd. | England | |
| ABM Technical Solutions Limited | England | |
| ABM Onsite Services - Canada ULC | Canada | |
| ABM General Services, Inc. | Delaware | |
| ABM Healthcare Support Services, Inc. | Michigan | |
| ABM Industrial Services, Inc. | Delaware | |
| ABM Industry Groups, LLC | Delaware | |
| ABM Security Services, Inc. | California | |
| ABM Texas General Services, Inc. | Delaware | |
| OneSource Facility Services, Inc. | Delaware | |
| ABM Building & Energy Solutions, LLC | Delaware | |
| ABM Building Services, LLC | Delaware | |
| ABM Building Solutions, LLC | Delaware | |
| ABM Electrical Power Services, LLC | Delaware | |
| ABM Electrical Power Solutions, LLC | Delaware | |
| ABM Electrical & Lighting Services, LLC | Delaware | |
| ABM Electrical & Lighting Solutions, Inc. | Delaware | |
| ABM Facility Support Services, LLC | Delaware | |
| RenewEnergy Solutions, LLC | Delaware | |
| ABM Franchising Group, LLC | Delaware | |
| Grade Sub Two, LLC | Delaware | |
| GCA Services Group, Inc. | Delaware | |
| Associated Facility Management, LLC | Nevada | |
| GCA Cleaning Specialties, LP | Texas | |
| GCA Services Group Mountain States, LP | Texas | |
| GCA Services Group of Texas, LP | Texas | |
| Associated Facility Ventures, LLC | Nevada | |
| GCA Education Services, Inc. | Tennessee | |
| GCA Education Services Central States, Inc. | Illinois | |
| GCA Education Services of New England, Inc. | Delaware | |
| GCA K12 Education Services, Inc. | Texas | |
| GCA Nuclear Facility Services, Inc. | Texas | |
| GCA Plumbing Services, Inc. | Delaware | |
| GCA Production Services, Inc. | Delaware | |
| GCA Services Group of California, Inc. | California | |
| GCA Services Group of Colorado, Inc. | Colorado | |
| GCA Services Group of North Carolina, Inc. | North Carolina | |
| GCA Services Group of Northwestern States, Inc. | Washington | |
| GCA Specialty Services LLC | Florida | |
| GCA Staffing Services, Inc. | Delaware | |
| National Building Maintenance Corp. | Delaware | |
| IFM Assurance Company | New York | |
*Subsidiary relationship to Company or to subsidiary parents shown by progressive indentation.