The transactional paradigm states that people create, maintain, and change their environments according to their personalities. At the same time, the environment reacts back on personality. As social relationships are part of an individual's environment, this likewise implies that there are reciprocal transactions between personality and relationships. However, earlier studies have concluded that adult personality traits are so stable that they have a stronger effect on later relationships, but that relationship effects on personality are negligible. In this article, we contend that personality-relationship transactions should be revisited. We submit that the relative powers of personality versus relationship effects depend on the type of life transition during which the effects take place: Relationship effects on personality development are more likely to emerge in the context of rather normative and highly scripted life transitions, whereas personality effects on relationship development are more likely to occur in the context of rather non-normative life transitions that are less regulated by social expectations. We illustrate these assumptions with examples from our own work and other findings reported in the literature. Furthermore, we theorize that effects of personality-relationship transactions on health also vary with the normativeness of the eliciting life transition.