Of 1 million cases of child maltreatment identified every year in the United States, one-fifth result in foster care. Many of these children suffer from significant emotional and behavioral conditions. Decision-makers must allocate highly constrained budgets to serve these children. Recent evidence suggests that Multidimensional Treatment Foster Care for Preschoolers can reduce negative outcomes for these children, but the relative benefits and costs of the program have not been evaluated. The objective of this study was to assess net benefit, over 24 months, of Multidimensional Treatment Foster Care for Preschoolers compared to regular foster care. Data were from a randomized controlled trial of 117 young children entering a new foster placement. A subsample exhibited placement instability (n = 52). Intervention services including parent training, lasted 9-12 months. Multidimensional Treatment Foster Care for Preschoolers significantly increased permanent placements for the placement instability sample. Average total cost for the new intervention sample was significantly less than for regular foster care (full sample: $27,204 vs. $30,090; P = .004; placement instability sample: $29,595 vs. $36,061; P = .045). Incremental average net benefit was positive at all levels of willingness to pay of zero or greater, indicating that the value of benefits exceeded costs. Multidimensional Treatment Foster Care for Preschoolers has significant benefit for preschool children in foster care with emotional and behavioral disorders compared to regular foster care services. At even modest levels of willingness to pay, benefits exceed costs indicating a strong likeliness that this program is an efficient choice for improving outcomes for young children with emotional and behavioral disorders in foster care.