► This study explored the impact of maternal interaction on emotional regulation using the Still Face Paradigm. ► A longitudinal study design was used with infant–mother dyads seen at 4 and 9 months. ► More maternal contingent responding was associated with infants who had more positive affect at both 4 and 9 months. ► More Maternal Attention Seeking play resulted in decreased positive affect at both 4 and 9 months. This study used the Still Face Paradigm to investigate the relationship of maternal interaction on infants’ emotion regulation responses. Seventy infant–mother dyads were seen at 4 months and 25 of these same dyads were re-evaluated at 9 months. Maternal interactions were coded for attention seeking and contingent responding. Emotional regulation was described by infant stress reaction and overall positive affect. Results indicated that at both 4 and 9 months mothers who used more contingent responding interactions had infants who showed more positive affect. In contrast, mothers who used more attention seeking play had infants who showed less positive affect after the Still Face Paradigm. Patterns of stress reaction were reversed, as mothers who used more attention seeking play had infants with less negative affect. Implications for intervention and emotional regulation patterns over time are discussed.