Little research has examined associations between low-income married couples' daily interactions and severity of disagreements. Similarly, few researchers have considered how family-strengthening interventions for low-income couples may affect the quality of daily interactions and associations between interactions and conflict experiences. This study aims to fill these gaps in the literature by leveraging daily diary data from a random assignment study of a family-strengthening intervention with low-income husbands and wives 30 months postenrollment. Married couples randomly assigned to the intervention participated in 10 weeks of relationship education services. Control group couples received no services. Thirty months postrandom assignment, participants reported on the severity of daily marital disagreements over a 15-day period, as well as their positive and negative emotions during inter-spousal interactions. Multi-level models demonstrated associations between reports of emotions in interactions and severity of disagreements. In addition, wives assigned to the family strengthening program reported fewer negative emotions during interactions at follow-up than wives in the control condition. Finally, negative associations between positive emotions in interactions and severity of disagreements were stronger for wives assigned to the intervention, while positive associations between negative emotions in interactions and severity of disagreements were weaker for wives assigned to the intervention. Implications for future research and intervention development are discussed.