| Index | Mountainside | New Jersey | National |
| Average Test Scores | 77% | 52% | 48% |
| Student/Teacher ratio | 12:1 | 13:1 | 16:1 |
| Total public schools | 3 | 1,604 | 79,221 |
| Total private schools | n/a | 823 | 24,874 |
| Total post-secondary schools | n/a | 157 | 7,963 |
| Index | Mountainside | New Jersey | National |
| Completed 8th grade | 93.4% | 87.5% | 84.3% |
| Completed high school | 93.4% | 86.3% | 83.0% |
| Completed some college | 78.6% | 60.7% | 59.4% |
| Completed associate degree | 64.9% | 43.9% | 38.5% |
| Completed bachelors | 54.8% | 37.5% | 30.3% |
| Completed masters | 24.5% | 14.4% | 11.5% |
| Completed professional degree | 9.1% | 4.0% | 3.3% |
| Completed doctorate | 2.6% | 1.5% | 1.3% |
There are a total of 3 public schools, n/a private schools and n/a post-secondary schools in Mountainside. Using the proficiency score averages, the average test scores for Mountainside, NJ schools is 77%. The average student to teacher ratio is 12:1. In Mountainside, NJ, an average of 93.4% of students have completed 8th grade and an average of 93.4% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Essex Fells, NJ | 2,164 | 85% | 75.6% |
| Short Hills, NJ | 12,771 | 83% | 73.3% |
| Mountain Lakes, NJ | 4,287 | 83% | 72.2% |
| Singac, NJ | 4,793 | 82% | 70.4% |
| Summit, NJ | 21,895 | 81% | 68.9% |
| Mountainside, NJ | 6,835 | 77% | 60.0% |
| City | Population | Avg. Test Scores | National Avg. |
| Milford, OH | 6,833 | 78% | 61.3% |
| Maple Glen, PA | 6,837 | 81% | 68.3% |
| Greenville, IL | 6,833 | 36% | 26.2% |
| Sullivan, MO | 6,838 | 63% | 31.3% |
| Winthrop Harbor, IL | 6,832 | 43% | 11.2% |
| Mountainside, NJ | 6,835 | 77% | 60.0% |
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