California has over 3 million children ages 5 and under, with a large proportion living in poverty or with non-English-speaking parents. Quality early childhood education is important for future success, but the state system is marked by low wages, inconsistent standards, and insufficient monitoring. Child care is expensive and doesn't meet the needs of nonstandard schedules. California has a large proportion of children in care with no standards, and identifying young children with disabilities is inadequate. There is no centralized data collection system for evaluating improvement efforts.

This report examines the effects of preschool or childcare exposure on cognitive and social development before kindergarten, focusing on intensity and duration of attendance, and how this varies across different income and ethnic groups. The authors utilize data from a nationally representative sample of young children with rich family background information. Findings are important for debates over extending free preschool and which groups of children would most benefit.