ABSTRACT
Self-expansion theory is one of the first psychological theories of love, and arguably the first to focus on how romantic relationships influence a person’s sense of self. Over the past 40 years, a robust literature has supported the notion that people are motivated to expand their self-concepts, and romantic relationships are a central avenue for self-expansion. In this paper, we revisit the origins of self-expansion theory to determine how well the literature has tested its original tenets and identify key ideas that remain unexplored. We then review the current empirical literature, discuss how core constructs have been operationalized, highlight untested aspects of the original theory, and describe an agenda for future work.