- Comstock Communications, Inc.
- Conair Group Inc.
- Concordia Lutheran Ministries
- Conemaugh Health System
- Conemaugh Memorial Medical Center
- Conemaugh Meyersdale Medical Center
- Conemaugh Miners Medical Center
- Conemaugh Nason Medical Center
- Conference Archives Inc.
- Confluence Technologies, Inc.
- Consolidated Engineers
- Construction General Laborers Local 373
- Consultant
- Cornell Abraxes
- Cornerstone Care Community Health Centers of Greensboro and Rogersville
- Corporal Michael J. Crescenz Medical Center
- Corry Memorial Hospital
- County of Adams
- County of Allegheny Special Events
- Crawford Ellenbogen LLC
- Creehan-McHenry Inc.
- Crown Cork and Seal, Inc.
- Crozer Chester Medical Center
- Crozer-Keystone Health System
- CTR Systems Inc.
- Cynthia K. Franck's Child Care Centers
- Dan Rice Days
- DeAnglo Brothers
- Delaware County Memorial Hospital
- Deloitte Consulting
- Denham-Vitalie Design Associates
- Dentsply International
- Desmone and Associates
- Development Dimensions Intl.
- DHHS, OPHS, Region III
- Dick's Sporting Goods
- Dietrich Industries, Inc.
- Digital Designs Inc.
- Direct Feedback
- Do-Co Ceramics
- Document Solutions Group, Inc.
- Dofasco Tubular Product
- Dollar Bank
- Donate Life Pennsylvania
- Double Tree Hotel Philadelphia
- Doubletree Club Hotel, Philadelphia, Northeast, PA
- Downingtown Area School District
- Doylestown Hospital
- Drexel University
- Drexel University, Graduate Nursing Programs