Achievement goal researchers have demonstrated that performance-approach goals predict grades but do not affect interest, whereas mastery-approach goals predict interest in academic subjects but do not usually predict grades (Harackiewicz, Barron, Tauer, & Elliot, 2002). Goal systems theory (Kruglanski et at, 2002) may help explain these effects. Performance goals may be strongly associated with a smaller range of academic behaviors than mastery goals, and these associations may explain why each goal creates its effects. The strong, narrow focus of performance goals may help students concentrate effort and reduce distractions. In contrast, the wide focus of mastery goals may make students prone to distractions, but also provide the opportunity to connect academics to other goals and interests. We present evidence from two studies showing that the academic behaviors that were judged to be important for pursuing achievement goals were more differentiated for performance than mastery goals. Furthermore, greater differentiation of academic behaviors partially mediated the relationship between performance goals and grades. In addition, mastery goals were strongly associated with a wider range of academic behaviors. These results demonstrate the utility of synthesizing achievement goal and goal systems theories.