Nurses' control over practice is essential to nursing care quality and fosters teamwork at the point of care delivery. This article describes a study to measure the impact of nurses' control over their practice from the perspective of teamwork. The purpose of this study was to measure the relationship of control over practice to the five following dimensions of teamwork: team structure, leadership, situation monitoring, mutual support, and communication. The study method was a secondary analysis of 456 surveys from registered nurses working in a five-hospital system. Study results demonstrated that the global measure of teamwork correlated with control over practice and nursing experience, but not with teamwork training. All five individual dimensions of teamwork were perceived as better for those who had a high level of control over practice compared to those who did not. In the discussion section, we consider situation monitoring since this dimension demonstrated an interaction effect between teamwork training and control over practice. Nursing control over practice demonstrates a positive relationship with teamwork and should be considered in future education, policy, and research efforts. Further study is needed to understand control over practice as a potential moderator or mediator of other predecessors of effective teamwork.