This document provides an overview of the OECD Teachers' Professional Learning Study, which examines policies that can support teachers' professional growth and development from initial teacher preparation through continuing professional learning. The study has two strands: Strand I focuses on initial teacher preparation and the first years of teaching, while Strand II examines continuing professional learning. The study uses a combination of literature reviews, country background reports, policy diagnostics, and stakeholder engagement to identify challenges and emerging principles in different systems. The goal is to support peer learning and provide evidence to inform policies that can strengthen teachers' professional learning over their entire careers.