Teacher commitment to school is an important factor of school efficacy and it has immediate influence on pupil success. It also conveys teachers' psychological attachment to the teaching profession. There are numerous positive results of teacher commitment to school. Committed teachers are more devoted to their work, are willing to contribute to the achievement of school goals and are less likely to leave their profession. Quality teacher retention has become a growing challenge in education systems across the world. Thus, it is important to determine the factors which affect teacher commitment. The aim of this study was to examine to which extent certain demographic and contextual teachers' characteristics, together with the perceived principal support, self-efficacy and collective efficacy contribute to the affective, normative and continuance teacher commitment to school. The results of the performed regression analyses indicate that principal support is the most significant predictor of affective and normative teacher commitment. Although principal support has had a significant contribution in explaining continuance commitment, this contribution is quite small. Teacher self-efficacy has not been proved to be a statistically significant predictor of teacher commitment, while collective teacher commitment has a statistically significant, but low contribution in explaining affective, continuance and normative teacher commitment.