The present study proposes a tripartite model of L2 reading strategy use, reading motivations, and general learner beliefs by examining the relationships among them in an L2 context. Reading strategy instruction was performed for 360 first-year university students enrolled in a reading-based course, in expectation of affecting their motivations and beliefs in the process. A tripartite model consisting of the three constructs was examined by structural equation modeling (SEM). The results showed strong multiple correlations between these three variables. Furthermore, ample evidence was provided to validate this model: (1) the interdependence across the constructs demonstrated from the developmental perspective, (2) the model's multiple correlations confirmed at the level of individual correlations, and (3) the interrelationship between the constructs corroborated by the cross predictability in multiple regressions. The tripartite model suggests that the interdependence is a promising resource for comprehension development in the L2 reading context, and that main idea strategy plays a vital role in the process of learning to read. The results and discussion provide several important implications for research and instruction.