Self-concept scales (Math, English, Parent Relations, Same-Sex Peer Relations, and Opposite-Sex Peer Relations) from the Australian Self-Description Questionnaire II (SDQII) were included in the National Educational Longitudinal Survey of 1988 (NELS:88). Mean differences that were based on responses by 17,544 (NELS:88) U.S. and 1,147 (SDQII normative archive) AustraIian students were small, and gender differences (girls higher for English and Same-Sex Relations but lower for Math) were similar for both countries. Structural equation models relating mathematics and English achievement scores, school grades, self-concepts, and school-average abilities replicated and extended previous results that were based on the internal/external frame of reference model and the big-fish-little-pond effect