This article examines the conditions under which interest groups interact with political parties. Existing research finds that interest group-political party interactions in most western democracies have become more open and contingent over time. The close ideological and formal organizational ties that once characterized these relations have gradually been replaced by alternative, more pragmatic forms of cooperation. However, most of this research stresses the importance of the structural factors underpinning these links over time and across countries, but sheds little light on the factors driving short-term interest group-party interactions. Here, by drawing on survey data on Spanish interest groups obtained between December 2016 and May 2017, this paper seeks to fill this gap by taking into account party status, issue salience, and a group's resources as explanatory variables. It shows that mainstream parties are the primary targets of interest groups, that groups dealing with salient issues are more likely to contact political parties, and that the groups with most resources interact with a larger number of parties.