What can the scholarship on global international organizations (IOs) tell us about the contributions of the executive head (EH) to organizational change? The empirics of IO studies frequently credit EHs with important changes, but these studies seldom consider EHs separate from the rest of the bureaucracy and thus make few theoretical claims about them. Consequently, it is difficult to assess whether this credit is warranted and why some heads are given more credit than others. This article argues that heads, such as World Bank President Robert McNamara and United Nations Secretary‐General Dag Hammarskjold, were influential because they did not just channel state and bureaucratic demands but made political choices that contributed to organizational adaptation. To make this argument, it draws on sociological institutionalist and constructivist scholarship on IO and leadership to develop an analytical framework where IO adaptation is linked to the EH's performance of two tasks commonly associated with executive leadership: defining a strategic plan and mobilizing support to implement that plan. However, it adds that when environmental constraints are severe, the conventional “follower‐oriented” mobilization strategies found in leadership studies are less viable. Instead, EHs can adopt an “opposition‐oriented” one intended to prevent the opposition from mobilizing while incrementally implementing key reforms.