This research examines the mediating effect of teachers' proactive behaviour (PRB) on the relationship between teacher self-efficacy (TSE) and organisational commitment (OCO), applying structural equation modelling (SEM) to test the hypothesised relations among these latent constructs. Since the data are cross-sectional in nature, the results must be interpreted as suggestive of associations, rather than as conclusive causal influences. The research involved 311 school teachers from Turkey, with 141 males (45.3%) and 170 females (54.7%), representing diverse educational levels, including pre-school (6.8%), elementary (11.6%), middle school (18.3%), high school (41.2%), and other schools (22.2%). Data were collected using three validated instruments: The Proactive Behaviour Scale (PRB), the Teacher Self-Efficacy Scale (TSE), and the Organisational Commitment Scale (OCO). Confirmatory factor analysis (CFA) was conducted using AMOS 22, while descriptive statistics were analysed using SPSS 22.00. The results indicate a positive and statistically significant correlation among teachers' proactive behaviour, self-efficacy, and organisational commitment. Furthermore, the findings confirm that proactive behaviour partially mediates the relationship between self-efficacy and organisational commitment, highlighting its role as a significant yet incomplete intermediary in this dynamic. These insights contribute to a deeper understanding of how self-efficacy and proactive behaviour collectively influence teachers' commitment to their organisations.