High school graduation is the culmination of a successful K-12 education and the gateway to college or employment. Students who do not graduate face the prospect of unemployment or low-paying jobs. There are persistent gaps in academic achievement among students of different races, ethnicities and incomes.

In 2021, 95% of the 2017-18 Brookline cohort graduated, higher than the state rate of 90%. This was an increase of 3 percentage points from 2006 for Brookline, compared to a gain of 10 points for the state. Brookline's rate was similar to Newton and Arlington school district rates (96% and 95% respectively) and higher than rates in Cambridge (91%) and Everett (83%).

Brookline district students from low-income backgrounds graduated at a lower rate, 83% in 2021. Graduation rates were higher among Asian (98%) and white (96%) students in 2021, compared to Latino (91%) and African American (86%) students. Massachusetts had similar disparities, but students of all backgrounds graduated at higher rates in Brookline than at the state level.

Since 2006, the Brookline cohort graduation rate for Latino students increased the most (up 9 points), while the rate among African American students declined by 5 points. Rates for Asian, white, and economically disadvantaged students saw small increases of 1 to 2 points.

Studies point to a variety of factors believed to contribute to disparities in graduation rates and other measures of student achievement. School systems in the United States are highly segregated, and students of color disproportionately attend schools with high proportions of low-income students who may not have benefited from early learning opportunities at the same rate as other students. Schools also have different levels of resources, ranging from qualified/experienced teachers, to advanced courses to facilities and technology, and schools with large Black and Latino populations often have lower levels. In addition, teachers across all school systems tend to be disproportionately white, and teaching practices and curriculum may not be culturally relevant to students of color.

Students are included in the cohort based on the year they entered Grade 9. Students are transferred in or out of cohorts if they transfer schools. Students who earn a GED or Certificate of Attainment are not counted as graduates. Students are considered economically disadvantaged if their family participates in one or more of the following state-administered programs: the Supplemental Nutrition Assistance Program (SNAP); the Transitional Assistance for Families with Dependent Children (TAFDC); the Department of Children and Families' (DCF) foster care program; or MassHealth (Medicaid).