- Conrad Public Library
- Conseco
- Consolation Reunion Committee, Inc.
- Consolidated Bank and Trust co.
- Consolidated Cigar Company
- Consolidated Contracting Services, Inc.
- Consolidated Engineers
- Consolidated Laboratory Services
- Constella Group
- Construction General Laborers Local 373
- Construction Management Consultant Group Corp
- Construction Specifications Institute
- Consultant
- Consulting Engineers and Land Surveyors of California
- Consumer Electronics Association
- Consumer Healthcare Products Association
- Contemporary Long Term Care of New York
- Contempory Long Term Care of California
- Continental Airlines
- Continental Teves
- Continuing Care Communities
- Continuing Life LLC
- Contra Costa Health Services
- Contract Chemicals, Inc.
- Contract Environments Inc.
- Contract Pharma
- Contract Resource Group Inc.
- Control Corporation of America
- Convene of Orange
- Convene, The Journal of the Professional Convention
- Convenemachine
- Convenience Distribution Association
- Convent Avenue Baptist Church
- Convent of the Holy Names
- Convention and Visitors Association of Lane County Oregon
- Convention Industry Council
- Convention Sales Professionals International
- Convention Services of the Southwest, Inc.
- Convergent Technologies, Inc.
- Convergys
- Conway Regional Health System
- Cook Children's Medical Center
- Cook County
- Cook County North Shore Hospital
- Cook Hospital
- Cook Inc.
- Cook-Witter Inc
- Cooke County United Way
- Cookeville Regional Medical Center
- Cooley Dickinson Hospital