We developed and began construct validation of the Measure of Adolescent Heterosocial Competence (MAHC), a self-report instrument assessing the ability to negotiate effectively a range of challenging other-sex social interactions. Development followed the Goldfried and D'Zurilla (1969) behavioral-analytic model for assessing competence. Approximately 700 adolescents participated in 5 systematic studies. Studies 1 through 4 generated the MAHC item and response content, as well as the basis for response scoring. In the first 3 studies, extensive data were collected from the target population regarding problematic heterosocial situations and potential responses to those situations. In Study 4, expert jdudges rated the relative effectiveness of the adolescent-identified behavioral responses. In the final study, scale reliability and construct validity of the resulting 40-item multiple-choice self-report instrument were examined. Factor analysis yielded no interpretable factors, and the internal consistency of the total scale was acceptable (? =.73). Investigation of convergent and discriminant validity revealed that the MAHC was significantly related to measures of general social competence and anxiety in heterosexual situations and was not associated with a measure of socioeconomic status. Contrary to expectations, the MAHC was not correlated with peer ratings of social acceptance.