The article discusses how teacher librarians can transform their school library into a common learning environment for students, teachers, and colleagues that meets the needs of 21st century teaching and learning. Teacher-librarians should partner with teacher technologists and other learning specialists to capitalize on the school library's resources, technologies, and expertise available to improve best-practice teaching and student learning. The program elements of a learning commons, which includes learning literacies, knowledge-building, learning with technology and collaboration, are discussed.