Crash rates among teenagers are highly elevated during the first months of licensure. Parent-imposed driving restrictions on initial driving privileges can reduce exposure to high-risk driving conditions, thus reducing crash risk while teens' driving proficiency develops. This report describes the effect of the Checkpoints Program on driving limits and outcomes. Connecticut teens who obtained a learners permit over a 9-month period were recruited, providing a final sample of 3743 who obtained driver licenses. Families were randomized to the intervention or comparison condition. Intervention families received by mail a series of persuasive communications related to high-risk teen driving and a parent-teen driving agreement, while comparison families received on the same schedule general information on driving and vehicle maintenance. Relative to the comparison group, teens and parents in the Checkpoints Program reported significantly greater limits on high-risk teen driving conditions at licensure, 3-, and 6-months post-licensure; and intervention teens reported significantly less risky driving at each reporting period. By the 12-month follow up teens in the intervention group were significantly less likely than those in the comparison group to have had a traffic violation. However, no treatment group effect was found for crashes. This is the first study to report significant effects on teen driving behavior and performance of education designed to increase parental-imposed teen driving limits.