| IRON Workers Annuity Fund | Related tax-exempt org | Employee benefits | MA | 042647320 |
| IRON Workers Pension Fund | Related tax-exempt org | Employee benefits | MA | 042591016 |
| IRON Workers District Council Labor Managementcorp Trust | Related tax-exempt org | Contractor association | MA | 043216519 |
| IRON Workers Union Local No 7 | Related tax-exempt org | Labor union | MA | 041473615 |
| IRON Workers Local 7 Joint Apprentice Committee | Related tax-exempt org | Education of apprentic IRON workers | MA | 046110167 |
| A & a Window Products | Related taxable corporation/trust | — | MA | — |
| A G F Steel INC | Related taxable corporation/trust | — | MA | — |
| A T R Sales INC | Related taxable corporation/trust | — | MA | — |
| AAW Welding & Testing INC | Related taxable corporation/trust | — | MA | — |
| ABLS Rebar LLC | Related taxable corporation/trust | — | NH | — |
| Accord Steel & Precast Erector | Related taxable corporation/trust | — | MA | — |
| Action Steel LLC | Related taxable corporation/trust | — | CT | — |
| Aetna Bridge | Related taxable corporation/trust | — | RI | — |
| AJAX Construction CO INC | Related taxable corporation/trust | — | RI | — |
| Algar Construction Corp | Related taxable corporation/trust | — | MA | — |
| Altered Steel Construction Corp | Related taxable corporation/trust | — | RI | — |
| AMB IRON | Related taxable corporation/trust | — | NH | — |
| Andella IRON INC | Related taxable corporation/trust | — | MA | — |
| Anvil Steel Engineering INC | Related taxable corporation/trust | — | MA | — |
| Apcon INC | Related taxable corporation/trust | — | MA | — |
| ARC Erecting INC | Related taxable corporation/trust | — | ME | — |
| Atlantic Bridge & ENG | Related taxable corporation/trust | — | NH | — |
| Atlas Professionals USA LLC | Related taxable corporation/trust | — | TX | — |
| Aztec Steel INC | Related taxable corporation/trust | — | MA | — |
| BADD BROS INC | Related taxable corporation/trust | — | MA | — |