| Abbreviation | Definition |
|---|---|
| MHS | Montclair High School |
| MHS | Montebello High School |
| MHS | Montgomery High School |
| MHS | Montwood High School |
| MHS | Mooresville High School |
| MHS | Morgantown High School |
| MHS | Mundelein High School |
| MHS | Murphysboro High School |
| MHS | Muscatine High School |
| MHSA | Maine High School Assessment |
| MHSA | Milwaukee High School of the Arts |
| MHSA | Montana High School Association |
| MHSCP | Marietta High School Career Pathways |
| MHSP | Minimum High School Program |
| MHSS | Malayan High School of Science |
| MHSS | Middletown High School South |
| MHSS | Monk's Hill Secondary School |
| MHTS | Michael Hall Theatre School |
| MHU | Morgan Hill Unified School District |
| MICS | Mountain Island Charter School |