| # | Company name | Role | # of projects |
|---|---|---|---|
| 221 | Coplan | Structural engineering | 4 |
| 222 | Coplan Polska Sp. z o.o. | Structural engineering | 1 |
| 223 | Core Design, Inc. | Structural engineering | 1 |
| 224 | Cornerstone | Structural engineering | 0 |
| 225 | Cornerstone Engineering | Structural engineering | 1 |
| 226 | Cornerstone Structural Engineering Consultants | Structural engineering | 0 |
| 227 | Cornerstone Structural Engineering Group | Structural engineering | 4 |
| 228 | Cornforth Associates | Structural engineering | 0 |
| 229 | Correia Consulting | Structural engineering | 0 |
| 230 | Corsmit Raadgevend Ingenieursbureau | Structural engineering | 43 |
| 231 | Costa & Associates | Structural engineering | 6 |
| 232 | Cottrell/valdos & Associates | Structural engineering | 1 |
| 233 | Coughlin Porter Lundeen | Structural engineering | 25 |
| 234 | COWI AB | Structural engineering | 5 |
| 235 | COWI Gulf A/S Bahrain | Structural engineering | 4 |
| 236 | Coyne et Bellier | Structural engineering | 5 |
| 237 | CPE Structural Consultants Ltd. | Structural engineering | 3 |
| 238 | Craft & Webster Structural Engineers Inc | Structural engineering | 1 |
| 239 | Craig A Cartwright & Assocs | Structural engineering | 1 |
| 240 | Craig Maloney P E | Structural engineering | 0 |