Personal relationships are frequently studied using methods and analyses that reflect an interest in relationships as between-persons phenomena. Although informative, there is much to be learned from examining relational phenomena from a within-persons perspective. The present article reviews the application of within-persons approaches to both the conceptualization and investigation of relational phenomena. The benefits of studying variation in psychologically meaningful constructs across multiple relationships, across different contexts within a relationship, and across time are outlined. Moreover, combinations of between- and within-persons strategies that can examine how relational, contextual, and temporal variation differs across people are discussed. Methodological and statistical considerations important to such designs are also outlined, and their limitations are discussed.
There are more truths in twenty-four hours of a man's life than in all the philosophies.
—Raoul Vaniegem (1967/1979)