Four studies evaluate the new Self Description Questionnaire II short-form (SDQII-S) that measures 11 dimensions of adolescent self-concept based on responses to 51 of the original 102 SDQII items and demonstrate new statistical strategies to operationalize guidelines for short-form evaluation proposed by G. T. Smith, D. M. McCarthy, and K. G. Anderson (2000). Multiple-group confirmatory factor analyses revealed that the factor structure based on responses to 51 items by a new cross-validation group (n = 9,134) was invariant with the factor structures based on responses to the same 51 items and to all 102 items by the original normative archive group (n = 9,187). Reliabilities for the 11 SDQII-S factors were nearly the same and consistently high (.80 to .89) for both groups. Multitrait-multimethod analyses support the internal validity of responses over time. Gender and age effects on the 11 SDQII-S factors were invariant across the archive and cross-validation groups.