Good relationships are characterized by frequent positive social interactions, such as having fun together, sharing laughs, doing kind things for one another, and expressing gratitude. Here, building on rapidly emerging findings, I articulate core features of positive interpersonal processes for the first time. This approach leads to useful specificity in predictions about relationship consequences and simultaneously contributes to both affective and relationship science, two domains that span disciplines within the psychological literature. In turn, basic research on everyday positive interpersonal processes points toward new avenues for understanding the well-established links between good relationships and health.