This publication discusses how to create sustainable and high quality teacher capacity development systems for primary and secondary education, technical and vocational education and training, and higher education. Quality teaching is vital to meet the increasingly complex needs of students as they prepare for further education and work in the 21st century. The publication showcases 14 case studies from around the world as examples of teacher professional development programs that support, improve, and harness teaching capabilities and expertise. It also discusses government initiatives and other factors that can contribute to quality teaching.