| C Lazy Three Press |
| CAK Publishing |
| California-Princeton |
| Canyon Press Entertainment |
| Canyonlands Nat Hist Assn |
| Canyonlands Publications |
| Carl Sams |
| Carson Dellosa Publishing |
| Carson Enterprises |
| Cataract Lode Mining Company |
| Caxton Printers |
| Celeste Black |
| Center for Land Grant Studies |
| Centerplate |
| Chamisa Books |
| Charlesbridge Publishing |
| Chelsea Green |
| Cheyenne & Arapahoe Tribes |
| Christi Cage |
| Chronicle Books |
| Cinco Puntos Press |
| Cities In Color |
| City of Westminster |
| Clear Creek Publishing |
| Clear Light Publishers |
| CNU Colorado |
| Coastwide Tag & Label |
| Collier Publishing |
| Colorado Geological Survey |
| Colorado Mountain News Media |
| Colorado Photographics |
| Colorado Railroad Museum |
| Colorado Whistle Pig |
| Columbine Ink |
| Computer Lab |
| Consortium Book Sales |
| Conversational Navajo Pubs |
| Cooperative Extension Service |
| Cosmic House |
| Cosmic Ray |
| Council Oak Books |
| Cowgirl Peg Enterprises LLC |
| Crabtree Publishing |
| Creative Living Publications |
| Crown Peak Publishing |
| Cruden Bay Books |