Purpose: Perceived support from co-workers and managers is important for many organizational outcomes. However, the benefit of competence support from colleagues and school management on personal teacher efficacy has not been investigated. The purpose of this paper is twofold: first, to investigate the impact of competence support from colleagues and the school management on growth in teacher efficacy and second, to investigate cultural differences (Canada and Sweden). Design/methodology/approach: The authors administered an inventory measuring support for competence and personal teacher efficacy to over 400 teachers in Canada and Sweden at 27 schools, at two times. Time 1 took place at the first week of a fall semester and Time 2 at the end of the same semester. Findings: Structural equation modeling revealed that competence support from colleagues predicted growth in teacher efficacy, whereas competence support from school management did not. No differences in these relations emerged between Canadian and Swedish teachers. Practical implications: The findings have implications for how schools organize teachers in teacher teams so that competence support from co-workers is promoted. Originality/value: This study is the first cross-cultural study to empirically show that teachers' self-efficacy is significantly benefitted by competence support from their teacher peers.