Teacher self-efficacy for teaching in diverse classrooms is an important factor in the successful implementation of inclusion. Quantitative examinations of teacher self-efficacy have found the construct to be correlated with both contextual and teacher-related factors. In-depth qualitative exploration into type, quality, and nature of experiences that shape teachers’ self-efficacy beliefs is scarce. This research aimed to qualitatively examine potential sources of teacher self-efficacy and generate an explanation for the complex growth pattern it follows during the early years of practice. Seventy-eight beginning teachers across Canada (i.e., graduating teacher candidates and new teachers who are in the first three years of their practice) participated in 139 semi-structured interviews conducted over four years to address questions regarding the factors and experiences that influence their self-efficacy or confidence to teach in diverse classrooms. Ten factors which either had a positive or negative connotation emerged from a qualitative content analysis of their interviews. The Positive-Negative Experiences Balance (PNEB) model was conceptualized to understand and represent how these ten factors interactively, simultaneously, and collectively influence the development of beginning teachers’ self-efficacy for inclusive practice in the initial years of their careers. Through a comparison of frequency counts of codes, it was noted that beginning teachers differentially relied on experiential factors to enhance their self-efficacy when they were graduating, or were in the first three years of their teaching. The results are discussed in light of the relevant extant research. Implications of these results for teacher education programs and school leadership are also shared. / Graduate