The aims of the current study were to meta-analytically examine whether 1a) mid-morning cortisol values, 1b) mid-afternoon cortisol values, and 1c) the cortisol increase from mid-morning to mid-afternoon is higher within children when at child care compared to when at home; 2) an increase in cortisol from mid-morning to mid-afternoon at child care correlates with lower child care quality, more difficult child temperament, larger group size, and more hours at child care (all studied separately), and 3) certain study characteristics (year of publication, age group(s), research design, country, type of care, method of saliva collection, and the inclusion of covariates) moderate the outcomes of the former research questions in case of heterogeneity. (author abstract)