Based on the experiences analyzed in this book, both in OECD countries and in Latin America, and despite the wide variety of contexts, a number of factors can be identified that have a positive impact on teacher professional development. The study concludes that sound policies are necessary to ensure that teacher professional development equips teachers with the competencies they will need throughout their long careers. Society needs good teachers, whose professional practice meets high professional standards and who, above all, fulfill a fundamental commitment: to respect students’ right to learn.