Adolescents who use the Internet regularly (the "e-teen") present a new set of challenges for marriage and family therapists. This article introduces marriage and family therapists to (a) the basic technological concepts and unique psychological characteristics of the Internet important in understanding and addressing adolescent online sexual behavior, (b) the appropriate developmental expectations for teens online, including risk-taking behaviors and critical decision-making skills, and (c) suggested strategies for assessment, prevention, and intervention when dealing with problematic online sexual behavior in adolescents. Marriage and family therapists cannot ignore the role the Internet plays in adolescent sexual development and its implication for the family. This article will serve as a primer for the marriage and family therapist when presented with adolescents who engage in online sexual behaviors.