ABSTRACT Prior large-scale research on teacher collaboration and autonomy has failed to distinguish effects within and between schools or among elementary and middle school teachers. This lack of research has implications for professional development in countries like Korea, where national policies have increasingly favoured teacher collaboration. We therefore employed multilevel structural equation modelling to analyse Teaching and Learning International Survey 2018 responses from 5,601 Korean elementary and middle school teachers. Our findings revealed significant direct and indirect effects among the variables of teachers’ perceptions of teacher collaboration, teacher autonomy, school climate, team innovativeness and school satisfaction. At the teacher level, the main differences between elementary school and middle school teachers related to classroom autonomy and team innovativeness. Collaboration and autonomy significantly predicted school satisfaction among elementary school teachers but not middle school teachers. There were also key differences in effects from teacher collaboration and classroom autonomy at the teacher and school levels. The most notable finding was that school climate mediated the relationship between classroom autonomy and school satisfaction at the teacher level. As these factors relate to the uptake and implementation of professional development, we provide key recommendations for local and national policy-makers hoping to optimise learning opportunities for teachers.