A two-wave panel study was conducted among adolescents (Mean age = 14.78; N = 639) to examine the relationship between using sexually explicit websites and sexual initiation with particular attention to adolescents' pubertal status. Structural equation modeling and logistic regression analysis indicated that frequent users of sexually explicit websites were five times more likely to initiate sexual intercourse than nonusers. Pubertal status moderated this relationship: an increased likelihood to initiate sex was found among adolescents in an early pubertal stage who frequently viewed sexually explicit websites. However, a lower likelihood to initiate sex was found among adolescents in an advanced pubertal stage. The possibility of a reciprocal relationship was also examined but was not supported.