Governments around the world are increasingly investing resources for young children, and universal provision of early childhood education and care (ECEC) has become widespread. Children’s development is affected by the investments they receive both within and outside the household. A simple theoretical framework predicts that the provision of public childcare will improve children’s development if it offers more stimulation than the care it replaces. Generally, carefully designed studies show that the provision of early childcare is beneficial, especially for children from disadvantaged backgrounds. This is in line with expectations that the alternative care experienced by children from less affluent, less educated, and immigrant backgrounds is likely to be of lower quality. Interestingly, however, studies show that the children who would benefit the most are least likely to receive care, providing a challenge for policy makers. Some programs, such as the $5-per-day childcare in Quebec, have negative effects and therefore may be of poor quality. However, comparing results across programs that vary in several dimensions makes it difficult to separate out the ingredients that are most important for success. Studies that focus on identifying the factors in ECEC that lead to the greatest benefit indicate that some standard measures such as staff qualifications are weakly linked to children’s outcomes, whereas larger staff–child ratios and researcher-measured process quality are beneficial. Spending more time in high-quality childcare from around age 3 has proved to be beneficial, whereas the effect of an increase in childcare for younger children is particularly sensitive to each program’s features and context.
