ABSTRACT The search for dispositional factors that influence the course and conduct of close relationships has long and popular roots. No cogent theory of interpersonal processes would deny that dispositional factors matter, and, furthermore, both scholarly and lay analyses often emphasize them. Although existing research has made progress in understanding how dispositions affect behavior in ongoing relationships, when all is said and done, this progress has been modest. In this paper, we discuss several interlocking theoretical and methodological principles that may facilitate movement to the next (and more sophisticated) generation of theory and research. We draw particularly on interdependence theory to discuss the concepts of relationship and persons-in-relationship. Central to our analysis is the principle that interaction in relationships is an inherently dynamic, temporal, and thoroughly interdependent process that cannot be properly understood from examination of the static, global dispositions of one of its members. To provide grounding for our analysis, we also discuss several specific implications of these concepts for the conduct of research seeking to understand personality in relationships.