The first step toward examining the question : what do students' motivational goals and self-concept have to do with academic achievement?

We propose that student achievement can be more fully explained by examining the dynamic interaction among students' goals and academic self-concept. To unify these two motivational perspectives, it is necessary to examine the psychometric properties of both students' goals as defined by the General Achievement Goal Orientation Scale (GAGOS) and students' academic self-concept as defined by the Academic Self Description Questionnaire (ASDQ) to determine whether these measures (items and scales) remain independent and stable when combined in the one instrument. Hence, we test the ability of a hypothesised first-order measurement model, comprising goal orientation and academic self-concept, drawn from the GAGOS (McInerney, 1997) and ASDQ (Marsh, 1992), to fit three waves of data collected from 1001 high school students.