Student retention policies are found to have positive immediate effects although these tend to dissipate over time. There is still no consensus on the impact of retention on high school student achievement and graduation; though there is suggestive evidence that early-grade retention can be more effective than later-grade retention.

Summer school can be an effective short-term tool to increase test scores among low-performing students, especially those in later-grades. Alternative policies such as placement with highly qualified teachers, additional daily instruction, and individualized plans can also be used to increase the effectiveness of overall retention policies and help underperforming students achieve grade-level proficiency.