The purpose of this study was to gain a clearer understanding of the relation between parents’ knowledge of their emerging-adult children and emerging adults’ risk behaviors. Participants included 200 undergraduate students between the ages of 18 and 25 (121 women, 78 men; M age = 19.59, SD = 1.62) and both of their parents. Results revealed that knowledge of the emerging-adult child’s activities varied as a function of parent- and child-reports, and that child outcomes associated with parental knowledge were generally positive, including less drinking, drug use, and risky sexual behavior (although this varied as a function of reporter). The links between maternal knowledge and lower drug and alcohol use were particularly strong in the presence of maternal closeness. Implications for understanding the parent–child relationship during the transition to adulthood were discussed.