The impact of behavioral research on military systems design is often limited. Typically, military, technical, economic, and political systems designers are more influential. The implementation of a new leadership model-developmental leadership-in the Swedish Armed Forces may constitute an exception. The aim of this article is to describe and evaluate the implementation process and its effects. The new leadership model is now well on the way to full-scale implementation. The conclusion is that an interplay between structural aspects (limited organization size and the formal authority of the supreme commander) and behavioral and attitudinal aspects (internal and external change agents) contributed to this outcome.