Across Massachusetts, legislators, policymakers, educators, families, and communities are engaged in important conversations about whether to continue using student performance on the MCAS tests as part of the state's high-school graduation requirements. This document presents lessons drawn from 15-plus years of research on educational opportunity and state testing in Massachusetts by analyzing the Massachusetts Department of Elementary and Secondary Education database, which contains each student's MCAS scores, demographic characteristics, and K-12 enrollment/graduation status. This information was then linked to data about students' college enrollment, college success (i.e., remediation and grades), college graduation, and labor market earnings. For college outcomes, data was used from both the National Student Clearinghouse and the Massachusetts Department of Higher Education. For labor market outcomes, Massachusetts unemployment insurance data was used. The six main findings include: (1) Students' MCAS test scores and high-school course grades both predict long-term outcomes; (2) Students who score just above the competency determination (CD) threshold on the MCAS tests enroll in college at low rates and do not earn a living wage by age 30, on average; (3) While most students meet the CD testing standard on their first attempt, nearly all of those who fail are English learners (ELs), students with disabilities, and/or students with inadequate course preparation; (4) Passing the MCAS matters: Students who barely pass the test on their first attempt have better outcomes than those who just fail it; (5) While most students who initially fail go on to retake the test and pass, about 85% of those who never pass are English learners or students with disabilities; and (6) Most high schools that boost test scores also improve long-term outcomes like earnings. However, some schools, including some career and technical education (CTE) schools, improve students' long-term earnings without raising test scores, while other schools may overly focus on test preparation at the expense of broader skill development. [This report was developed in partnership with the Massachusetts Department of Higher Education.]