The academic impact of the transition from elementary to middle school has significant consequences for many early adolescents. This study examines academic growth across the transition, as well as sociodemographic moderators. Rather than defining the transition effect as a decline in student achievement between fifth and sixth grade, these data demonstrate the transition effect as an interruption in students’ growth in achievement during this interval. Results confirm larger interruptions for vulnerable students (e.g., low income, special education) despite closing the gap effect over the third- to eighth-grade interval.