Groundbreaking research on learning and cognition has produced many new insights into how people learn. These findings conclusively dispel the idea that short-term and isolated learning experiences can produce powerful learning. This is especially true for teacher learning, given the complexity of teaching and the multifaceted role expert teachers must play. Teacher learning programs must become more collegial, in-depth, and longer in duration and must be tailored to the experience levels of the learners, be they novice or expert teachers.