The time children spend in childcare overlaps with daily meals and opportunities to be active. Thus these environments have the opportunity to promote--or hinder--healthy weight gain among children who attend them. The purpose of this narrative review was to compile findings from studies examining childcare type and weight outcomes among preschool-age children. A literature search was conducted using PubMed, PsychInfo and ERIC. Inclusion criteria were infant- to 5-year-old children exposed to any type of childcare with a cross-sectional or longitudinal weight outcome. Among 385 studies screened, 18 were included. For comparison across studies, type of childcare was categorized as: childcare center, Head Start, nanny/babysitter, non-relative care/family childcare home and relative care. Four studies found no association with childcare type and obesity, and 10 studies reported mixed results by type of care or subpopulation analyses. Two studies found an overall positive association, and two reported an inverse association. There were differences in direction of associations and findings by type of care arrangement. For Head Start, three of eight studies demonstrated a negative relationship with obesity; none demonstrated a positive association. No other childcare type demonstrated this inverse association. Informal types of care (relative and non-relative care in a home) were positively associated with child obesity in 3 of 10 studies. This association was less commonly reported among formal childcare centers (2 of 15 studies). The majority of studies, however, reported mixed findings or no association by childcare type. Results suggested no consistent evidence for a relationship between childcare and obesity risk, except Head Start. This review exposed the need for a consistent definition of childcare type and the exploration of unmeasured confounders, such as the nutrition and physical activity environment of childcare settings, to understand how they contribute to or protect against the development of overweight/obesity among children. (author abstract)