The 1980s and 1990s witnessed a surge of psychological research addressing the role of affect in social judgments. Evaluations of others were shown to be shaped, at least in part, by a person's incidental mood in the moment of social evaluation; while negative moods instigated negative interpersonal evaluations, positive moods instigated positive interpersonal evaluations. Interestingly, these effects only emerged when the reason for the evaluator's mood was not obvious. Over 30 years later, we expand these findings to the dyadic domain. Rather than conceptualize interpersonal evaluations as occurring solely within an individual, we introduce the Dyadic Affect Infusion/Diffusion (DAID) model to suggest that interpersonal evaluations occur as fundamentally dyadic phenomena. Using 6 weeks of daily diary data from 311 couples in which one member approached a stressful event, we show that (a) mood influences relationship evaluations at both the intraindividual (i.e., affect infusion) and interindividual (i.e., affect diffusion) levels, (b) both affect infusion and affect diffusion are turned off by the availability of attributional information, and (c) these effects are better explained by affect infusion/diffusion rather than by several alternative mechanisms. Taken together, the DAID model bolsters the view that individualistic approaches to emotion and social cognition are insufficient and require theory and data at the dyadic and group levels of analysis. (PsycInfo Database Record (c) 2022 APA, all rights reserved).