The Children's Services Council (CSC) of Palm Beach County funded Chapin Hall at the University of Chicago to conduct a 6-year longitudinal study to examine the use and effectiveness of an array of services in the county in promoting school readiness and school success and improving family functioning among children and families most in need of support. The goal of the study is to describe the characteristics and needs of families the service system is intended to serve; how they use the services that make up the service system in Palm Beach County; and how service use is related to child and family outcomes. This report presents findings from the fourth year of in-person interviews conducted when the focal child was between 36 and 42 months of age and makes comparisons with findings from the first, second, and third years. In all analyses, the authors use 335 as the sample population, which is the number of mothers who completed all four waves of the in-person interviews. One of the clearest findings to emerge from this study thus far is the disadvantaged status of foreign-born children relative to those born in the United States. As of the fourth year of the study, these children were more likely to be living at or below the poverty level, despite the fact that their caregivers were more likely to be married or living together. In addition, some groups of foreign-born mothers reported significantly higher levels of depression and parenting stress, while others exhibited significantly lower levels of parenting skills. Most importantly, based on mothers' reports, the children of foreign-born Hispanic mothers appeared to be lagging in their development when compared to the children of other mothers. Given their relative disadvantaged status, it is encouraging to note that foreign-born mothers, and foreign-born Hispanic mothers in particular, were more likely to receive treatment services from the MCHP system. On the other hand, the authors did not find evidence that receipt of treatment services had a significant impact on maternal or child outcomes, at least as measured by this study. This suggests that it might be beneficial to examine whether and/or how treatment services offered by the system could be made more effective for all mothers, and especially for foreign-born mothers. While foreign-born mothers, and foreign-born Hispanic mothers in particular, were more likely to receive MCHP treatment services, foreign-born mothers overall used fewer services outside of the MCHP system when compared to U.S.-born mothers. Given that the MCHP system was successful in engaging foreign-born mothers in services, there may be ways that CSC could positively impact the provision of services to immigrant families by federal/state programs and agencies not funded by CSC. Finally, CSC might want to increase the amount of resources it devotes to assisting families with language, literacy, technical and other knowledge needed to navigate the application (and re-application) process for federal, state and other programs. Appended are: (1) Longitudinal Study Sample and Methods; and (2) Additional Data Tables. A bibliography is included. (Contains 100 tables, 2 figures and 82 footnotes.) [For the third annual report, "Supporting Low-Income Parents of Young Children: The Palm Beach County Family Study," see ED504250.]