We examined the influences of attachment orientations on within-person changes in affect as a function of perceptions of the interaction partner’s agreeable behavior in interactions involving a romantic partner and other kinds of partners. Working adults reported affect, perceptions of the other person’s behavior, and the relationship with the other in interpersonal events during 20 days. As expected, the within-person association between perceived partner’s agreeable behavior and negative affect was stronger for individuals higher on attachment anxiety and was weaker for individuals higher on attachment avoidance. These effects were more pronounced in interactions with a romantic partner than with other persons. Findings demonstrate that attachment orientations are associated with differing within-person processes and that these processes are sensitive to kind of interaction partner. (PsycINFO Database Record (c) 2011 APA, all rights reserved)