The urge to move to music is apparent even in young infants, and musical interactions between parents and infants have demonstrable effects on infant affect and physiology. Music is often experienced collectively, but little is known about how infants respond to musical performances in group contexts. Here, we examined infants’ attention, affect, and rhythmic movements while watching infant-directed performances by professional musicians. Across two sessions, 56 parent-infant dyads were video-recorded while watching a live musical performance. All dyads watched under two conditions: parents were instructed to either avoid or to engage in interacting musically with their infants (passive/interactive), with condition order counter-balanced with song type (lullaby/play-song) across sessions. Play-songs especially captured infant attention, while lullabies encouraged infants to direct attention to their parent and others around them, regardless of the interactive context. Play-songs elicited more positive affect than lullabies, especially in the interactive context. As directed, infants and parents moved together more in the interactive than passive condition, but infants still often initiated movement in the passive condition, suggesting that in the absence of parent-initiated movement, infants still link movement to musical contexts. Overall, results suggest that song type influences infants’ attention and affect in group music settings, and that the interactive context additionally modulated their affect. This study provides the first investigation of infants’ attention to live music in group contexts with high ecological validity, and the early musical movements documented here may set the stage for later, more sophisticated musical interactions with others.