This literature review is one of several components of the Measurement Development: Quality of Caregiver-Child Interaction for Infants and Toddlers (Q-CCIIT) project, funded by the Office of Head Start (OHS) within the Administration for Children and Families (ACF), U.S. Department of Health and Human Services (DHHS), and with involvement of staff from the Office of Planning, Research, and Evaluation (OPRE/ACF/DHHS). The main purpose of the Q-CCIIT project is to develop a new measure to assess the quality of caregiver-child interactions within varied nonparental care settings for infants and toddlers. Specifically, the new quality measure will be appropriate for use in center-based and family child care settings, as well as in single-and mixed-age classrooms. Furthermore, the measure should be appropriate for use with diverse populations, such as children with disabilities and children whose home language is not English. (author abstract)