In this study, we evaluated CUIDAR, a program that provides community-based 10-week parent training to reduce attention and behavior problems in preschool children. We recruited 154 predominantly low-income and Latino preschoolers and their parents to participate in this evaluation study. We collected data prior to and immediately following intervention and one year later. At the time of follow-up, we also recruited 15 parents who had initially enrolled, but never participated in the program to serve as a comparison group for a limited set of analyses. From pre to post intervention, we observed significant, positive changes in eight out of ten measured parenting behaviors. From pre intervention to follow-up, improvements in the use of transitional statements and planning ahead were significant. Children's SDQ Total Difficulties scores significantly decreased from pre to post intervention (d = .36), and we observed significant, positive changes in all SDQ subscales. From pre intervention to follow-up, children's SDQ Total Difficulties scores significantly decreased (d = .71) and all SDQ subscales reflected significant, positive changes. We observed no significant differences in reported barriers to participation between parents who participated in the program and those who enrolled, but never participated. Intervention gains were moderated by several factors, including history of out-of-home care and family structure. Our results should be interpreted cautiously because not all analyses included a comparison group, and a randomized trial of CUIDAR effectiveness is still needed. © 2010 The Author(s).