Studies explaining interest organizations’ influence typically focus on the role of groups’ structural characteristics, such as group type. However, we ask whether the boards of interest groups can also play a role in their organizations’ advocacy performance. Drawing from management scholarship, we investigate how the governance practices and characteristics of the boards of interest organizations are associated with those organizations’ advocacy performance. To study this, we surveyed the board members of Finnish elite interest organizations and found that board performance in strategy tasks (e.g., long-term planning and connecting with stakeholders) is strongly related to advocacy performance. Moreover, we found that the gender diversity of boards is negatively associated with success in advocacy, and the frequency of board meetings is curvilinearly associated. In contrast, board performance in control tasks (e.g., monitoring of management), board size, and inclusive practices are not associated with advocacy performance.