The preschool-to-third grade perspective has helped the early childhood field move away from a reliance on relatively brief or one-shot programs toward more systematic and comprehensive models that span most of children's first decade. We review the knowledge base on the effectiveness of preschool-to-third grade intervention programs and practices for young children making the transition to school. Our coverage includes extended early childhood interventions, preschool programs, full-day kindergarten, reduced class sizes in the early grades, parent involvement, instructional practices, and school transitions (mobility). We distinguish between two major PK-3 strategies. PK-3 programs are planned interventions that begin during any of the five years of a child's life before kindergarten and which continue up to third grade. The most comprehensive programs include all these elements, and serve children from low-income families or who have special needs. Alternatively, PK-3 practices are defined as specific elements or components of extended early childhood programs that are hypothesized to be associated with children's outcomes. These elements may include preschool education, full-day kindergarten, reduced class sizes, teaching practices, and parent involvement activities. Overall, we find growing evidence for the positive effects of PK-3 programs and practices. The strongest evidence supporting enduring effects into adulthood is from center-based preschool programs followed by small classes in the early grades. Additional longitudinal studies are needed into adulthood to fully document the effects of different PK-3 programs and to verify the extent to which PK-3 practices (e.g., parent involvement, school mobility) have long-term effects into adulthood.
- Child development