The State of the Science conference was held in May, 2007 as part of the ongoing series of national conferences, "Building on Family Strengths," conducted by the Research and Training Center on Family Support and Children's Mental Health at Portland State University. The theme of this State-of-the Science conference was "Effective services for all children and families: Addressing disparities in children's mental health and other child-serving systems." Presenters and participants at this conference considered the special challenges presented by addressing the mental health needs of children, youth, and families from diverse ethnic, cultural, and geographic circumstances and the state of the science concerning these issues. The proceedings of this conference build on and are supported by the summer, 2007 issue of Focal Point, which addressed "Effective Interventions for Underserved Populations." The title of this issue encapsulates themes from the state of the science conference: (1) Who is underserved? What is the population or populations we are talking about? What do we know about disparities?; (2) What do we mean by "effective?" Effectiveness implies a change for the better. Key questions about effectiveness include, "Who should define the initial problem or need for change or development?" "Who should define what acceptable interventions or treatments are?" "Who should define and identify what successful outcomes are?" "What scientific methods are/can be used to answer questions about effectiveness regarding underserved populations?"; (3) What are the major barriers to achieving effective services and reducing disparities?; (4) What successful policies, programs, and services exist?; and (5) What are the key current and planned approaches to reducing disparities and promoting effective services for all? An index is included. Individual papers contain tables, figures, references and footnotes.