Graduation from high school is an important achievement for students, and one that has implications for their future educational opportunities and earnings. For the last two decades, graduation rates have also been among the metrics used to evaluate school effectiveness under federal law, with the aim of ensuring that all students receive a high-quality education. The stakes for schools and districts are high--including school prestige and risks to educators' reputations and employment if a school is perceived as falling short. Under the "Every Student Succeeds Act of 2015" (ESSA), all states use the same formula, known as the adjusted cohort graduation rate, to calculate how many students graduate from high school within the standard four years. Because states are not required to report the number of students who graduate after five or more years, many state accountability systems do not give schools credit for these graduates. The high stakes attached to the four-year graduation rate can have unanticipated and undesirable consequences for English Learners (ELs), as this report demonstrates, because these students are more likely than their peers to graduate after a fifth or sixth year. Among the most concerning: some high school administrators may turn away those who arrive as older teenagers, despite their eligibility to attend free public school, for fear that their enrollment could damage the school's graduation rate. And while research shows the importance of giving ELs access to grade-appropriate content while they learn English, some schools may feel pushed to accelerate newcomers' learning to maintain a four-year graduation trajectory, even when an extended timeline and additional support might be a better fit. When it comes time for ESSA's reauthorization, policymakers will have the chance to revisit how graduation rates are defined and given weight. The challenge, the author writes, will be finding a way to identify schools that are truly underserving their students, while preventing the undue penalization of others that serve students with more complex learning needs.