Routine, day-to-day interactions form the fabric of our interpersonal experience. A mother and her toddler, for example, might have a number of difficult moments in any given day as they jointly navigate the child's newly developing autonomy (e.g., the child wants to play with a forbidden toy). On the other hand, the majority of the day will typically be spent speaking about more neutral topics, such as eating, cleaning up, and getting dressed. Historically, clinical researchers have focused on more atypical, maladaptive interactions between children and their parents or peers, with the goal of reducing these aversive interactions. These maladaptive interactions are important. For example, negative interpersonal interchanges, in moderation, may allow for reflection and insight, offering important opportunities for adaptive change in relationships (Dunn & Brown, 1994; Lunkenheimer, Shields, & Cortina, 2007). However, they are also rare: Even with the most problematic children, observational researchers code only about 5% to 10% of family and peer interactions as aversive (Dishion, Duncan, Eddy, & Fagot, 1994). In contrast, adaptive neutral or positive interactions are not only more common, but we are more likely to observe them in the home and laboratory contexts. Further, an important goal of preventive intervention programs is to promote and build on existing adaptive interaction patterns in close personal relationships. Thus both adaptive and maladaptive interactions in close relationships should be of interest to clinical and developmental psychopathology researchers.