Implementing a planned change successfully is critical to organizations’ performance and depends on all members’ participation. Most research has studied leaders’ and middle managers’ role in planning and communicating change, not how frontline staff – those who deal directly with clients and customers, and their direct managers – ultimately implement it. This is surprising, especially in professionalized organizations, as involvement of frontline managers and professional staff is critically important to achieving change. This article reports on a comparative case study that examined how and why some acute care hospital units were more successful in implementing planned change. The data analysis identified change-facilitating and change-inhibiting microdynamics (activities and interactions) among frontline teams: managers and professional nursing staff at the hospital units, which resulted in more and less efficacious implementation of planned change and virtuous and vicious change cycles. The authors developed models that show how and why microdynamics differed in the units and offer guidance to managers in encouraging planned change at organizations’ front line.