This report describes intervention effects on parent-imposed driving limits on novice young drivers at licensure. Parent-adolescent dyads (4,344) completed baseline surveys at permit and were randomly assigned to intervention or comparison groups. Intervention families received persuasive communications related to protection motivation theory variables including threat appraisal regarding high-risk adolescent driving and coping appraisal regarding restrictions on high-risk driving conditions during the early months of adolescent licensure. Comparison families received standard information on driving, vehicles, and road safety. Among the 4,344 families, 3,786 adolescents obtained licenses, and 3,398 parent-adolescent dyads completed surveys at licensure. Significant treatment group differences favoring the Checkpoints Program were found at licensure for driving limits, perceived risk, expected limits, and outcome expectations. Perceived risk and outcome expectations partially mediated and expected limits fully mediated treatment effects. The results provide evidence that persuasive materials can alter threat and coping appraisal and expectations, thereby increasing parent-imposed driving limits at licensure.