| Abbreviation | Definition |
|---|---|
| MCA | Marion Cultural Alliance |
| MCA | Michigan Colleges Alliance |
| MCCA | Midwest Community Cat Alliance |
| MCCA | Myanmar Climate Change Alliance |
| MCFA | Minor Crop Farmer Alliance |
| MCGA | Manitoba Common Ground Alliance |
| MCGA | Mason County Growth Alliance |
| MCGA | Mendocino County Growers Alliance |
| MCRA | Molten Core Raid Alliance |
| MCTA | Mississippi Communications Technology Alliance |
| MCWA | Monocacy Catoctin Watershed Alliance |
| MDAA | Missile Defense Advocacy Alliance |
| MDRA | Marine Design Resource Alliance |
| MDSA | Metro Denver Shelter Alliance |
| MEAA | Media and Entertainment Arts Alliance |
| MEAA | Media Entertainment and Arts Alliance |
| MEAA | Media Entertainment Arts Alliance |
| MEAA | Media, Entertainment and Arts Alliance |
| MEAA | Mountain Empire Agency Alliance |
| MECA | The Middle East Childrens Alliance |