Prekindergarten children are being expelled from their classes for behavior problems at a higher rate than students in K-12 schools, a study released May 17 reveals. The study, which was conducted by Walter S. Gilliam, a psychologist and an associate research scientist at the Yale University Child Study Center, shows that for every 1,000 preschoolers enrolled in state pre-k programs, 6.67 are being tossed out of school, compared with 2.09 per 1,000 students in elementary, middle, and high schools. Expulsion rates are even higher for preschoolers enrolled in community-based programs. The research also shows that when teachers have access to mental-health professionals for consultation, the chance that a child will be permanently removed from preschool is far less. Mr. Gilliam recommends that states with public preschool programs write clear policies for how teachers and administrators can support young children with significant behavior problems, and design alternatives to expelling preschoolers. Those strategies might include having aides assigned to an individual child or even setting up alternative preschool programs with smaller class sizes and teachers with specialized training.