In this chapter, we review research to better understand how teams, communities of practice, and knowledge networks serve as locations for learning professional practice. We focus on the ties and relationships that connect the people who are actually doing the learning. The lines have blurred between individual learning, and the groups and communities people join to collaborate to reach goals and solve problems. Individual motivation, learning, and performance are the starting point; but such learning is often intrinsically connected to social learning, informal, and embedded in unique work contexts. A key question is how do different kinds of work arrangements and relationships lead to not only an overall enhancement of worker competencies and stocks of knowledge but organizational capabilities to produce integrated solutions responsive to evolving problem situations. Our review suggests a focus today on process rather than structure, which implies an inherently dynamic process of forming, renewing, and reshaping collective and reciprocal relationships in ways that respond to shifting needs and problems.