| # | Company name | Role | # of projects |
|---|---|---|---|
| 441 | Cameron Taylor Bedford Limited | Consultancy | 0 |
| 442 | Camp Dresser And Mckee | Consultancy | 1 |
| 443 | Campbell Reith LLP | Consultancy | 3 |
| 444 | Campbell Reith LLP | Consultancy | 0 |
| 445 | Canaveral Technigraphics Co | Consultancy | 1 |
| 446 | Canham Consulting Limited | Consultancy | 0 |
| 447 | Cannell Reprographics | Consultancy | 1 |
| 448 | Cannon & Associates Inc Consulting Engineers | Consultancy | 0 |
| 449 | Cansult Maunsell | Consultancy | 5 |
| 450 | Cape Dixson & Associates (cdai) | Consultancy | 0 |
| 451 | Capita Symonds Ltd. | Consultancy | 17 |
| 452 | Capital Charette | Consultancy | 0 |
| 453 | Capital Engineering | Consultancy | 0 |
| 454 | Capital Imaging | Consultancy | 0 |
| 455 | Capitol Market Research | Consultancy | 1 |
| 456 | Caplan Engineering Co. | Consultancy | 0 |
| 457 | Cara Blueprint Express | Consultancy | 1 |
| 458 | Carl Blueprint | Consultancy | 0 |
| 459 | Carl Bro Group | Consultancy | 8 |
| 460 | Carlson Testing | Consultancy | 1 |