This study aims to unify two substantial literatures relating to student motivation by proposing a more comprehensive model of students' motivation than has recently been provided to date. Notably, students' goal orientations, as operationalised by the General Achievement Goal Orientation Scale (GAGOS), and students' academic self-concept as operationalised by the Academic Self Description Questionnaire II (ASDQ II); are combined in one instrument in order to: (a) examine the psychometric properties of the combined instruments and (b) investigate the interrelated multidimensional and hierarchal structure of motivation and self-concept. Data collected over three years from 535 Australian High School students confirm the hypothesis that students' goals and academic self-concepts are interrelated components of an overall model of student motivation. Furthermore, this model remains stable and invariant across sex and over time. The model presents a unified framework within which the interaction among students' goals and academic self-concept may be investigated more fully.