A transsexual course of development that starts before puberty (early onset) or during or after puberty, respectively (late onset), may lead to diverse challenges in coping with sexual activity. The authors explored the sexual behavior of 380 adult male-to-female and female-to-male individuals diagnosed according to DSM-IV-TR criteria who had not yet undergone gender-confirming interventions. Data originated from the European Network for the Investigation of Gender Incongruence Initiative, conducted in Belgium, Germany, The Netherlands, and Norway. Information on outcome variables was collected using self-administered questionnaires at first clinical presentation. Compared with late-onset male-to-females, early-onset individuals tended to show sexual attraction toward males more frequently (50.5%), involve genitals less frequently in partner-related sexual activity, and consider penile sensations and orgasm as more negative. Early-onset female-to-males predominantly reported sexual attraction toward females (84.0%), whereas those with a late-onset more frequently showed other sexual attractions (41.7%). The study (a) shows that early- and late-onset male-to-females differ considerably with regard to coping strategies involving their body during sexual relations and (b) reveals initial insights into developmental pathways of late-onset female-to-males.