- American Society for Therapeutic Radiology and Oncology
- American Society of Association Executives
- American Society of Consultant Pharmacists
- American Society of Health System Pharmacists
- American Society of Mechanical Engineers
- American Society of Nephrology
- American Society of Pediatric Nephrology
- American Society of Pension Professionals and Actuaries
- American Society of Safety Professionals
- American Society of Transplant Surgeons
- American Society of Transplantation
- American Society on Aging
- American Solar Energy Society
- American Soybean Association
- American Sportscaster
- American Standard
- American Statistical Association
- American Subcontractors Association
- American Trust and Savings Bank
- American Urological Association
- American Viet League Hiep Hoi My Viet)
- American Water Resources Association
- American Water Works Association
- American Water Works, Inc
- American Way Van and Storage, Inc.
- American Wind Energy Association
- AmericaWorkVisa AWV)
- Americna Management Association San Francisco
- Americo, Inc.
- Amerigroup
- Ameritex Linen, Inc.
- AMETEK, Inc.
- AMGEN, Inc.
- Ami Adini
- AMITA Health Adventist Hospital Hinsdale
- AMITA Health Adventist Medical Center Bolingbrook
- AMITA Health Adventist Medical Center GlenOaks
- AMITA Health Adventist Medical Center La Grange
- AMITA Health Mercy Medical Center Aurora
- AMITA Health Saint Francis Hospital Evanston
- AMITA Health Saint Joseph Hospital Chicago
- AMITA Health Saint Joseph Hospital Elgin
- AMITA Health Saint Joseph Medical Center Joliet
- AMITA Health Saints Mary and Elizabeth Medical Center Chicago
- AMITA Health St. Alexius Medical Center
- AMITA Health St. Mary's Hospital Kankakee
- AMK Drives and Controls Inc.
- Ammonoosuc Community Health Services, Inc.
- AMP Management Services
- Ampco-Pittsburgh Corporation