Mercer Island High School
Mercer Island, WA · High School · Grades 9-12
Mercer Island High School is a high school in Mercer Island, WA with 1,524 students enrolled and a 65% proficiency rate. Part of Mercer Island School District. NCES data from the U.S. Department of Education.
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About This School
Mercer Island High School is a high school located in Mercer Island, Washington. The school serves 1,524 students in grades 9-12. The student-to-teacher ratio is 20.6:1.
According to EDFacts assessment data, 65% of students meet grade-level proficiency standards in combined math and reading. The school reports a 85% graduation rate.
7% of students qualify for free or reduced-price lunch.
Mercer Island High School is part of the Mercer Island School District in Washington.
How This School Compares
Mercer Island High School has 1,524 students enrolled, making it larger than the average school in Mercer Island School District (676 students). Its 65% proficiency rate is 4 percentage points below the district average of 69%. Compared to the Washington state average of 49%, the school performs 16 points higher. The 20.6:1 student-teacher ratio is above the national average of 16:1.
Frequently Asked Questions
Mercer Island High School has 1,524 students enrolled in grades 9-12. The student-to-teacher ratio is 20.6:1.
According to EDFacts data, 65% of students at Mercer Island High School meet grade-level proficiency standards in combined math and reading assessments.
Mercer Island High School has a 85% graduation rate, measuring the percentage of students who graduate within four years.
Mercer Island High School is part of the Mercer Island School District in Mercer Island, Washington. You can view all schools in this district on the district page.
All data on this page comes from the National Center for Education Statistics (NCES) Common Core of Data and EDFacts assessment results. These are official federal datasets published by the U.S. Department of Education.
School profiles are built from NCES directory data and EDFacts assessment results. Proficiency rates reflect combined math and reading performance. Graduation rates are reported for high schools with available data.
For this entity, the underlying data on this page comes from NCES Common Core of Data and EDFacts. The breakdown above is the federal record; the paragraphs below add the per-entity context that makes the headline numbers usable for a real decision rather than just a data lookup.
Every number on this page links back to NCES Common Core of Data and EDFacts; the methodology page describes the inputs, refresh cadence, and known limitations of the underlying data product.
Practical use of this page is in combination with the comparison and ranking pages elsewhere on the site, which surface the same data for this entity’s peers within U.S. public schools and districts. A single-entity reading without peer context can be misleading when an entity is an outlier on one axis but typical on another.
Source: NCES Common Core of Data, 2026.