Using a qualitative research approach, this article explores teachers' roles in infants' play and its changing nature in an infant group care setting. Three infant teachers in a child care center were followed over three months. Observations, interviews, ongoing conversations, emails, and reflective notes were used as data sources. Findings revealed that the teachers took on various roles: observer, play follower/play partner, facilitator, commentator/interpreter, play supporter, play leader, play interrupter, safety/conflict manager, multiple-responder, and multiple-role taker. The nature of the teachers' roles developed and changed over time in relation to the infants' rapid growth, group dynamics, and infant-teacher relationships. This study suggests that infant teachers' practice is complex, changing, and developmental as the group care context is dynamic and multilayered. (Contains 2 tables.)