The aim of this study is to compare the overall characteristics of children at Aizone, an After-School Day Treatment Program, with those of their peers, as well as to examine changes in their functioning at home, school, and in the community after participation in the Aizone program. As a treatment center based on an integrated-developmental theory, Aizone is a Korean daytime treatment facility that offers not only individual and group treatment for children, but also provides community-linked services integrated with parent and family intervention. Aizone provides services for children with complex or severe emotional and behavioral problems, and is especially targeted towards children from low-income households. With the mission to promote the mental health of children and youth through early intervention, Aizone was established in 2006, and as of 2016, has been implemented in ten locations throughout Seoul and is continuing to grow. This study investigates 201 students at Aizone with 186 controls in order to investigate the general characteristics of children attending Aizone. Also, in order to verify the effectiveness of the program, we measured changes in the children. However, unlike previous studies, which focus on reduction of symptoms, we used the Child Adolescent Functional Assessment Scale to analyze changes in behavior, academics and peer relationships, emotion, and several special areas. According to the results, children at Aizone showed significant improvements in various aspects of function except addiction problems. Implications of the results are discussed.