The Adaptive/Maladaptive Perfectionism Scale (AMPS) for children measures different dimensions of perfectionism. In this study, subscales derived from the AMPS were compared with results of the Piers-Harris Self-Concept Scale (PHSCS) in a sample of fourth- and fifth-grade students (9 to 11 years old). The AMPS dimensions accounted for significant variation in PHSCS scores for both boys and girls, though the specific patterns of results differed between the sexes. For boys but not girls, greater sensitivity about making mistakes was only problematic, in terms of predicting negative aspects of self-concept, under conditions of lower self-esteem. Results provided additional psychometric support for the AMPS and revealed important considerations for assessment and intervention with perfectionistic children. (Contains 2 tables and 3 figures.)