Drowning is responsible for an estimated 320,000 deaths a year, and over 90% of drowning mortality occurs in low- to middle-income countries (LMICs), with peak drowning rates among children aged 1 to 4 years. In this age group, mortality due to drowning is particularly common in rural settings and about 75% of drowning accidents happen in natural bodies of water close to the home. Providing adequate child supervision can protectchildren from drowning, and organized formal day care programs could offer a way to achieve this. Primary objective • To assess the effects of day care programs for children under 6 years of age on drowning-related mortality or morbidity, or on total drowning accidents (fatal and non-fatal), in LMICs, compared to no day care programs or other drowning prevention interventions Secondary objectives • To assess the effects of day care programs in LMICs for children under 6 years of age on unsafe water exposure • To assess safety within these programs (e.g. transmission of infection within day care, physical or sexual abuse of children within day care) • To assess the incidence of unintentional injury within these programs • To describe the cost-effectiveness of such programs, in relation to averted drowning-related mortality or morbidity SEARCH METHODS: On November 23, 2019, and for an update on August 18, 2020, we searched MEDLINE (PubMed), Embase, CENTRAL, ERIC, and CINAHL, as well as two trial registries. On December 16, 2019, and for an update on February 9, 2021, we searched 12 other resources, including websites of organizations that develop programs targeted to children. We included randomized, quasi-randomized, and non-randomized controlled studies (with explicitly listed specific study design features) that implemented formal day care programs as a single program or combined with additional out-of-day care components (such as educational activities aimed at preventing injury or drowning or early childhood development activities) for children of preschool age (below 6 years of age) in LMICs for comparison with no such programs or with other drowning prevention interventions. Studies had to report at least one outcome related to drowning or injury prevention for the children enrolled. Two review authors independently performed study selection and data extraction, as well as risk of bias and GRADE assessment. Two non-randomized observational studies, conducted in rural Bangladesh, involving a total of 252,631 participants, met the inclusion criteria for this review. One of these studies compared a formal day care program combined with parent education, playpens provided to parents, and community-based activities as additional out-of-day care components versus no such program. Overall we assessed this study to be at moderate risk of bias (moderate risk of bias due to confounding, low risk of bias for other domains). This study showed that implementation of a formal day care program combined with parent education, provision of playpens to parents, and community-based activities, in a rural area with a high drowning incidence, likely reduces the risk of death from drowning over the study period of 4 years and 8 months compared to no day care program (hazard ratio 0.18, 95% confidence interval [CI] 0.06 to 0.58; 1 study, 136,577 participants; moderate-certainty evidence). Drowning morbidity (non-fatal drowning resulting in complications), total drowning (fatal and non-fatal), unsafe water exposure, and program safety (e.g. transmission of infection within day care, physical or sexual abuse of children within day care) were not reported, nor was the incidence of other unintentional injuries. Cost-effectiveness was reported as 812 USD (95% CI 589 to 1777) per disability-adjusted life-year averted as a consequence of drowning (moderate-certainty evidence). The second study compared day care programs with or without playpens provided to parents as an additional component versus only playpens provided to parents as an alternative drowning prevention intervention. Overall we assessed the study to be at critical risk of bias because we judged bias due to confounding to be at critical risk. As the certainty of evidence was very low, we are uncertain about the effects on drowning mortality rate of implementing a day care program compared to providing playpens (rate ratio 0.25, 95% CI 0.15 to 0.41; 1 study; 76,575 participants; very low-certainty evidence). Likewise, we are uncertain about the effects of a day care program with playpens provided as an additional component versus playpens provided alone (rate ratio 0.06, 95% CI 0.02 to 0.12; 1 study, 45,460 participants; very low-certainty evidence). The other outcomes of interest - drowning morbidity, total drowning, unsafe water exposure, program safety, incidence of other unintentional injuries, and cost-effectiveness - were not reported. This review provides evidence suggesting that a day care program with additional out-of-day care components such as community-based education, parent education, and playpens provided to parents likely reduces the drowning mortality risk in regions with a high burden of drowning compared to no intervention.