Objective: To examine developmental and behavioral status of children in child welfare (CW) over time, by intensity of CW involvement using a national probability sample., Methods: As part of the National Survey of Child and Adolescent Well-being (NSCAW), data were collected on 1,049 children 12-47 months old investigated by CW agencies for possible abuse or neglect. Analyses used descriptive statistics to characterize developmental and behavioral status across four domains (developmental/cognitive, language, adaptive functioning, and behavior) by intensity of CW involvement (in-home with CW services, in-home with no CW services or out-of-home care) over time. Multivariate analyses were used to examine the relationship between independent variables (age, gender, home environment, race/ethnicity, maltreatment history, intensity of CW involvement) and follow-up domain scores., Results: On average, children improved in developmental/cognitive, communication/language status over time, but these improvements did not differ by intensity of CW involvement. Analyses revealed a positive relationship between the home environment and change in language and adaptive behavior standard scores over time, and few predictors of change in behavioral status. An interaction between intensity of CW involvement and initial developmental/cognitive status was present., Conclusions: Across domains, intensity of CW involvement does not appear to have a significant effect on change in developmental and behavioral status, although out-of-home care does have differential relationships with children's developmental/cognitive status for those with very low initial cognitive/developmental status. Facilitating development in children in CW may require supportive, enriched care environments both for children remaining at home and those in foster care., Practice Implications: Toddler and preschool age children known to child welfare are likely to have difficulties with development whether they are removed from their homes or not. It would be helpful if child welfare workers were trained to screen for developmental, language, adaptive behavior and behavioral difficulties in children in foster care, and those remaining at home. Additional support for biological, foster, and kinship caregivers in encouraging development is important for the attainment of critical developmental skills, especially for children with developmental difficulties.