The majority of clinicians rarely take a history of their patients’ sexual behaviors and issues, especially those working with children and adolescents. This aspect of functioning should not be overlooked, however, as it could lead to clinical insights and allow adolescents to seek information about sexuality from a trusted adult. The current study evaluated a new measure designed to examine sexual behavior in high-risk adolescents; in particular, the ACSBI assesses sexual risk-taking, nonconforming sexual behaviors, sexual interest, and sexual avoidance/discomfort. Instrument scales include: Sexual Knowledge/Interest, Divergent Sexual Interests, Sexual Risk/Misuse, Sexual Fear/Discomfort, and Concerns About Appearance. The evaluation compared adolescents with a sexual abuse history to those without an abuse history on the range of sexual behaviors reported by themselves and their primary female caregiver. The study also examined various predictors of sexual behavior, such as demographic variables, maltreatment, and total life stress. Participants were 174 adolescents, ages 12 to 18 years and their primary female caregiver; 120 of the participants were involved in either partial or inpatient treatment for emotional and behavioral problems, while another 54 had been referred for an outpatient evaluation. Results of factor analysis indicated that parent- and self-reports of adolescent sexual behavior were moderately correlated. There was a noted heterogeneity of high-risk sexual behaviors within the clinical sample. There was a significant relationship between high-risk sexual behavior and emotional and behavioral problems, as well as sexual concerns, distress, and preoccupation. Other significant predictors of sexual behavior in adolescents included sexual abuse, physical abuse, life stress, and impaired family relationships. Assessment of the psychometric properties of the scale suggest that each measure and its individual scales have adequate reliability, with the exception of the Fear/Discomfort scale on both the self-report and parent-report versions. Future research should investigate more positive correlates of sexual behavior, including contraceptive use and seeking out sexual information from adults. Tables, references