Like other self-conscious emotions, shame takes on particular significance during late childhood and adolescence because of a developing capacity for self-reflection, self-other comparisons, and sensitivity to the views of others. Shame is a potentially important variable in adolescent well-being given its established associations with depression, reduced feelings of self-worth, and problematic anger. Three studies are reported that describe the development and validation of the Adolescent Shame-Proneness Scale (ASPS), a novel semi-idiographic measure of shame-proneness. The ASPS is a 19-item measure assessing 3 components of shame-proneness—negative self-evaluation, externalization, and emotional discomfort. Taken together, the studies support the reliability and validity of the ASPS as a semi-idiographic measure of shame-proneness in adolescents aged 11 to 18 years. ASPS scores correlate as expected with scores on existing measure of shame-proneness and with measures of anger, negative affect, and self-esteem. More important, the data suggest that ASPS scores are related to, but distinct from, guilt. Confirmatory factor analysis supported the validity of the ASPS factor structure (RMSEA = .08, SRMR = .05, CFI = .97, NNFI = .97). The ASPS represents a unique contribution to existing options for measuring shame-proneness in research and clinical contexts. Further work is required to assess the ASPS’ temporal stability and its viability and psychometric properties in more culturally diverse samples.