Participation refers to which children and providers are eligible to enroll in or offer services as part of Colorado’s universal preschool program. Though all 4-year-olds may be eligible to enroll, some are unable to participate because of geographic constraints or diversity of available providers. Upcoming decisions about expanded preschool, such as eligibility of program types (e.g., centers, family child care homes) may also impact provider participation. This brief explores factors that may affect child and provider participation in universal preschool. (author abstract)