The relationship between political parties and organized interests is critical to understanding democratic politics, yet few scholars have systematically studied this topic in recent decades. In the following essay, I review the American politics literature examining the interactions between parties and organized interests and assess the current state of our knowledge. I then argue that we should make more explicit and systematic use of the understanding of symbiotic relationships from the field of ecology, which is already either explicitly or implicitly used in many studies, to improve our understanding of interactions between parties and organized interests. By applying these ideas, we can better understand the formation and internal dynamics of symbiotic relationships between political parties and organized interests, as well as the larger questions of how party-organized interest interactions help to shape broader outcomes, which I discuss in the conclusion.