Although we did not test for statistical significance, differences in the typicality of the earliest sexual behavior were evident for most sociodemographic characteristics. The similar prevalence of oral-genital and vaginal intercourse in adolescence for some groups but not others indicate complex patterns of differential acceptance of oral-genital intercourse during adolescence across multiple sociodemographic indicators. In multivariate models, we found that these characteristics were significantly and uniquely associated with timing of sexual initiation. Some patterns (e.g., earlier mean age at first vaginal intercourse among non-Hispanic Black adolescents; associations between early pubertal timing and early coital transition) have been previously reported,28,29 but others are unique. For example, to our knowledge this is the first report of linkages between early pubertal timing and greater likelihood of oral-genital and anal intercourse experience during adolescence. Finally, our analyses indicate independence of demographic typicality of a sexual behavior and individual timing of initiation. Future research should examine whether different patterns (e.g., non-Hispanic Black adolescents who initiate oral-genital intercourse early in adolescence) have differential implications for individual sexual development and for population health.