Research shows that professional learning can have a powerful effect on teacher skills and knowledge, and on how well students learn. To be effective, however, professional learning for teachers needs to be conducted in the ways that it is in many high achieving countries--continuously, collaboratively, and with a focus on teaching specific content to particular learners. Studies of U.S. professional development show that a small minority of American teachers receive the kind of sustained, job-embedded professional development that research indicates can change teaching practice and improve student achievement. This brief looks at how high-achieving countries organize professional learning for teachers, and draws a set of policy lessons for the United States. (Contains 1 figure.)