Objective: The purpose of this study was to determine optimal criteria for defining response and remission in adolescents with acute mania. Method: Data were analyzed from three treatment studies of adolescents with acute mania (N = 99). Trained raters completed the Young Mania Rating Scale (YMRS), and clinicians completed the Clinical Global Impressions Scale for Bipolar Disorder (CGI-BP) independent of YMRS ratings. For response, the percentages of reduction in YMRS scores from baseline to endpoint were compared with CGI-BP Mania Improvement scores. For remission, endpoint YMRS scores were compared with CGI-BP Mania Severity scores. Signal detection analyses were conducted to evaluate the efficiency of selected cutoffs associated with response and remission. Results: A [greater than or equal to]55% reduction in YMRS scores from baseline to endpoint was the optimal cutoff defining response. An absolute endpoint YMRS score [less than or equal to]12 was the optimal cutoff defining remission. Conclusions: The results of this signal detection analysis in adolescent mania suggest that current commonly used cutoffs to define response ([greater than or equal to]50% reduction) and remission ([less than or equal to]12) may be appropriate with regard to efficiency. Studies with methods specifically tailored to evaluate and compare these rating scales and larger patient samples from multiple sites are needed to confirm these preliminary findings. (Contains 3 tables and 2 figures.)