The Office of the Assistant Secretary for Planning and Evaluation (ASPE), in partnership with the Administration for Children and Families (ACF) within the U.S. Department of Health and Human Services, funded Mathematica Policy Research and its partners to conduct the Learning About Infant and Toddler Early Education Services (LITES) project. LITES aimed to identify effective and replicable program models to support infant and toddler early learning in out-of-home early care and education (ECE) settings to inform future research, policy, and program directions at the federal, state, and local levels. LITES had two main components: (1) a systematic review to identify effective program models to support infant and toddler early learning in out-of-home ECE settings, and (2) a scan of the field for program models that are compelling but lack rigorous research examining impacts on children's developmental outcomes. For both components, we examined infant and toddler early learning models that targeted children's cognitive, language, or social-emotional/behavioral development. For the systematic review, we conducted a comprehensive literature review to identify studies with eligible research designs, rated the quality of the studies, and examined evidence of effectiveness on children's outcomes. In contrast, for the compelling models scan, we identified models through a nomination process and discussion with experts in the field. This report focuses on the systematic review; a second report focuses on findings from the compelling models scan (Del Grosso et al., 2015). (author abstract)