| # | Company name | Role | # of projects |
|---|---|---|---|
| 21 | Hanscomb Associates Inc. | Consultancy | 0 |
| 22 | Hanscomb Associates, Inc. | Consultancy | 3 |
| 23 | Hansford Durley Harban | Consultancy | 0 |
| 24 | Hargreaves Associates | Consultancy | 0 |
| 25 | Harlan Hanson Inc | Consultancy | 0 |
| 26 | Harlan Tait Associates | Consultancy | 1 |
| 27 | Harley Haddow Partnership | Consultancy | 1 |
| 28 | Harpen Aktiengesellschaft | Consultancy | 0 |
| 29 | Harper & Garratt Engrg. Inc | Consultancy | 0 |
| 30 | Harper Houf Peterson Righellis Inc | Consultancy | 1 |
| 31 | Harper Houf Peterson Righellis Inc | Consultancy | 0 |
| 32 | Harpster Engineering & Surveying Inc | Consultancy | 1 |
| 33 | Harris & Associates Inc | Consultancy | 1 |
| 34 | Harris & Sutherland Corporation | Consultancy | 1 |
| 35 | Harris Consultancy | Consultancy | 0 |
| 36 | Harrison & Taylor | Consultancy | 0 |
| 37 | Hartgen Archeological Associates Inc | Consultancy | 0 |
| 38 | Harvey Freeman | Consultancy | 1 |
| 39 | Harza Consulting Engineers | Consultancy | 1 |
| 40 | Hawley & Partners | Consultancy | 0 |