The purpose of the present study was to investigate the application of the Model of Reciprocal Causation (MRC) in examining the relationship between student personality (personal factors), student-perceived teacher interpersonal behavior (environment), and Mathematics achievement (behavior), with the simultaneous investigation of mediating effects and bidirectional relationships. The sample consisted of 317 Cypriot students and their 19 teachers. The relationship among the three constructs was examined using structural equation modeling. Results supported the mediating role of student perceptions of teacher interpersonal behavior in the personality-achievement relationship, and the unidirectional effect between student perceptions and achievement, with perceptions affecting achievement. Overall, the study demonstrated that the MRC provides a comprehensive and dynamic framework for examining the role of classroom interactions, student personal characteristics, and achievement. Implications for research and educational practice are discussed.