Abstract Feelings of affection (i.e., fondness and intense positive regard) are a hallmark of close relationships. Existing studies have often examined affection as a trait or behavior, but rarely as an emotional experience in social interactions. In two dyadic observational interaction studies (total N = 314 individuals), 49 US-based married couples (age range: 21–65) and 108 friendship dyads (age range: 15–26) engaged in two naturalistic 10-min conversations about (a) a topic of disagreement (conflict conversation) and (b) something they enjoyed doing together (pleasant conversation) and reported on their subjective emotional experiences (e.g., affection, using an emotion checklist following each conversation) and relationship satisfaction. Conversation transcripts were analyzed using natural language analysis. Results showed that experiences of affection were most strongly associated with experiences of compassion, amusement, and excitement, as well as with less anger, and were unrelated to most other negative emotions. Natural language analysis further showed that greater positive (but not negative) emotional tone was associated with greater affection (especially among friends in the pleasant conversations). Levels of affection were consistently higher in pleasant versus conflict conversations and similar across marital versus friendship interactions. Finally, experiences of affection were associated with greater relationship satisfaction for friends across conversations and for spouses (women) in the pleasant conversation. These findings contribute to our understanding of affection as a foundational emotional experience in close relationships and highlight avenues for future research.