As they write about the Learning Communities standard in "Reach the Highest Standard in Professional Learning: Learning Communities," authors Ann Lieberman and Lynne Miller consider why communities have gained widespread attention and support and summarize the established research base about them. They also describe three contexts in which professional learning communities have been enacted and consider the challenges professional learning communities face, concluding with an examination of the "questions professional communities raise and the implications they pose for school reform in general and the role of teachers in the reform agenda in particular" (Lieberman, Miller, Roy, Hord, & von Frank, 2013). This excerpt from their full chapter shares rationale and findings from research about learning communities.