The importance of understanding how interorganizational buyer–seller relationships are created, persist, sometimes destroyed and occasionally re-established has been raised in multiple contexts. For many reasons, continuity is a focal construct of interest in business marketing contexts. To date empirical research on buyer–seller relationships in business markets has largely concentrated on studying the status of an existing relationship, though, typically through cross-sectional investigations. Compared with longitudinal investigations, cross-sectional approaches have advantages, such as more cost effective data collection efforts. Many aspects of buyer–seller relationships in business markets evolve only slowly over time, in which cases cross-sectional studies are an acceptable approach. Considerably less attention has been devoted to the longitudinal aspects of relationships, though, so the objective of this chapter is to synthesize existing empirical research that examines the longitudinal aspects of buyer–seller relationships, with an eye to understanding how they form, evolve over time and sometimes break down.