The growing body of literature demonstrating the importance of quality interactions with caregivers to infant development coupled with the increasing number of infants spending time in classroom settings highlights the need for a measure of interpersonal relationships between infants and caregivers. This article introduces a new measure of quality in infant classrooms based on the Classroom Assessment Scoring System (CLASS) framework. This measure focuses on teacher-infant interactions with the goal of understanding how these proximal process features can be assessed in this environment. Results from a small pilot study of 30 infant classrooms indicated that the CLASS-Infant demonstrated adequate variability as well as expected convergent and divergent validity with the most commonly used infant child care quality measure. The dimensions of the measure composed a single construct of classroom quality based on teacher-infant interactions. Practice or Policy: Implications of using this measure as an assessment of center-based infant classroom quality and improving professional development are discussed. (author abstract)