Assessing sexual risk is critical for human immunodeficiency virus (HIV) and sexually transmitted infection (STI) prevention with adolescents. This article compares sexual risk reports from two self-administered instruments, a standard survey and a sexual health history calendar (SHHC), among racially diverse youth (n = 232) ages 14 to 21 seeking services at a public health clinic. Agreement between methods was assessed using Lin's concordance correlation coefficients (CCC) and Bland-Altman plots. Lin's CCC showed poor to moderate agreement between instruments on reports of sexual partners in the past 3 (0.47), 6 (0.55), and 12 (0.49) months. While individual sexual partner questions were refused a total of 179 times on the survey, youth reported having sexual partners during the same time period on the SHHC in most (77.1%) of these instances. Poor agreement was also found for condom use frequency (CCC = 0.17), with youth's frequency of condom use on the SHHC differing from that reported on the survey for more than half (55.6%) of the months they were sexually active. While lack of objective sexual behavior measures limits conclusions about the accuracy of reports, the ways in which youth's responses varied across instruments may offer insight into the complexity of adolescent sexual risk taking as well as have important implications for development of HIV/STI preventive interventions.