| Administration and Resources Management Support Staff | ARMSS |
| Air Division | AD |
| Air Pollution Prevention and Control Division RTP, NC | APPCD |
| Air Pollution and Control Division | APCD |
| Air Protection Division | APD |
| Air Quality Modeling Group RTP, NC | AQMG |
| Air and Radiation Division | ARD |
| Air, Pesticides, and Toxics Management Division | APTMD |
| Air, RCRA, and Toxics Division | ARTD |
| Alaska Operations Office | AOO |
| Alternative Dispute Resolution Law Office | ADRLO |
| American Indian Environmental Office | AIEO |
| American Management Systems | AMS |
| American National Standards Institute | ANSI |
| Assessment and Standards Division | ASD |
| Assessment and Watershed Protection Division | AWPD |
| Atmospheric Modeling Division, Ann Arbor | AMD |
| Atmospheric Protection Branch, RTP, NC | APB |
| Center for Exposure Assessment Modeling | CEAM |
| Certification and Compliance Division | CCD |
| Chemical Abstracts Service | CAS |
| Chemical Engineering Branch | CEB/OPPTS |
| Chesapeake Bay Program | CBPO |
| City of Milwaukee Health Department, Division of Disease Control and Prevention | DDCP |
| Clean Air Markets Division | CAMD |
| Climate Protection Division | CPD |
| Coalbed Methane Outreach Program | CMOP |
| Collection Strategies Division | CStD |
| Communications Division | CD |
| Compliance Assurance and Enforcement Division | CAED |
| Computer Sciences Corporation | CSC |
| Congressional and Intergovernmental Relations | OCIR |
| Cross Media Division | CMD |
| Cross-Cutting Issues Law Office | CCILO |
| Division of Enforcement and Compliance Assistance | DECA |
| Division of Environmental Planning and Protection | DEPP |
| Division of Environmental Science and Assessment | DESA |
| EPA-Systems Development Center | EPA-SDC |
| Effects Identification and Characterization Group | EICG |
| Emergency and Remedial Response Division | ERRD |
| Emission Factor & Inventory Group | EFIG |
| Emissions Characterization and Prevention Branch | ECPB |
| Emissions, Monitoring, and Analysis Division RTP, NC | EMAD |
| Enforcement Capacity and Outreach Office | ECOO |
| Enforcement Coordination Office | ECO |
| Enforcement Planning, Targeting, and Data Division | EPTDD |
| Engineering & Analysis Division | EAD |
| Environmental Accountability Division | EAD |
| Environmental Appeals Board | EAB |
| Environmental Assessment and Innovation Division | EAID |
| Environmental Assistance Division | EAD |
| Environmental Council of States | ECOS |
| Environmental Sciences Division Las Vegas, NV | ESD |
| Environmental Services Division | ENSV |
| European Environment Agency (EEA), European Topic Centre on Catalogue of Data Sources (ETC/CDS) | EEA/ETC/CDS |
| Federal Facilities Enforcement Office | FFEO |
| Federal Facilities Restoration and Reuse Office | OFFRR |
| Fibers and Organics Branch | FOB |
| Finance and Operations Law Office | FOLO |
| Global Programs Division | GPD |
| Great Lakes National Program Office | GLNPO |
| Gulf of Mexico Program Office | GMPO |
| HQ and Desktop Services Division | HDSD |
| Hazardous Site Cleanup Division | HSCD |
| Health & Ecological Criteria Division | HECD |
| Health Protection and Modeling Branch | HPMB |
| Human Exposure and Atmospheric Science Division RTP, NC | HEASD |
| Idaho Operations Office | IOO |
| Immediate Office | IO |
| Indian Environmental Office | IEO |
| Information Access Branch | IAB |
| Information Access Division | IAD |
| Information Exchange and Services Division | IESD |
| Information Management Center | IMPMC |
| Information Products Section | IPS |
| Information Resource Management Team | IRM team |
| Information Transfer Group, RTP, NC | ITG |
| Infrastructure Branch | IB |
| International Enforcement and Compliance Division | IECD |
| International Environmental Law Office | IELO |
| International Organization for Standardization | ISO |
| International Union of Pure and Applied Chemistry | IUPAC |
| Laboratory Operations Division | LOD |
| LandView Support | LVS |
| Landfill Methane Outreach Program | LMOP |
| Lewis Publishers | Lewis |
| Lockheed Martin Information Technology | LMIT |
| Logistics Management Institute | LMI |
| Management Division | MD |
| Management and Operations Staff | MOS |
| Merck and Co., Inc. | Merck |
| Michigan Department of Environmental Quality | MIDEQ |
| Michigan Department of Information Technology | MIDIT |
| Mid-Continent Ecology Division Duluth, MN | MED |
| Missouri Department of Natural Resources | MO, DNR |
| Monitoring Branch | MB |
| Monitoring Branch (IM) | MB/IM |
| Multimedia Planning and Permitting Division | MPPD |
| Municipal Assistance Branch | MAB |
| Municipal Branch | MB |
