This chapter discusses how and why design teams change, drawing upon our observations of and interviews with representatives of various design teams in regional and national offices, as well as our interviews with educators in schools. It explores that the loci of change are both the design teams as organizations and the reform models associated with them. The chapter examines how design teams evolve in response to growth in the use of their models, to school or district demands, and to political and market forces. It argues that design teams often change their organizational forms and their reform models even as they work with schools. The chapter then discusses the organizational changes that took place in design teams as a result of interactions with schools, state agencies, and funding sources. The dynamics of change within the design teams lend a “building the plane while it’s flying” quality to the entire scale up process.