In this chapter, the authors challenge the field to overcome its focus on internal states and behavioral precursors as a substitute for behavior, and offer instead a method for studying behavior in everyday contexts. Using marital conflict as a specific instantiation of an important social behavior, the authors describe the utility of daily diaries as a tool for the assessment of these behaviors. They argue that studying variability in behavior is as essential to understanding behavior as studying mean levels, and offer possibilities for statistical analysis of diary data that focus on such variability. The authors report a reanalysis of couples’ diary data originally published in Bolger et al. (1989) that focuses on questions of variability in marital conflict and reactions to those conflicts. The authors describe how this analysis of variability led to insight about couple conflict that was not apparent from their original analyses.