Preschoolers who spend their days with mom rather than in day care are less likely to go on to careers as troublemakers and class clowns. That’s one conclusion to be drawn from the largest and longest-running study of American childcare, the federally financed Study of Early Child Care and Youth Development, which released its long-awaited results March 26. Specifically, the investigators reported that keeping a preschooler in a day care center for a year or more increases the likelihood that the child will become disruptive in school at least through sixth grade. The research project began in 1991 and is still ongoing. The investigators have financing to follow the same children into high school and are proposing to follow some into their 20s. The results should make headlines even if they’re not at all surprising.