Despite their shared focus on groups, research bridging intragroup processes and intergroup relations is surprisingly rare. The goal of the present article is to highlight how understanding the reciprocal relationship between intragroup processes and intergroup relations offers valuable new insights into both topics and suggests new, productive avenues for research and theory development – particularly for understanding and improving intergroup relations. The article next briefly reviews key findings from three dominant frameworks in the field of intergroup relations: social cognition, social identity, and functional relations. It then discusses the complementary role of intergroup and intragroup dynamics, reviewing how intergroup relations can affect intragroup processes and then discussing how intragroup dynamics can shape intergroup relations. The final section considers the implications, theoretical and practical, of the proposed reciprocal relationships between intragroup and intergroup processes.