Noting that there is a group of young children for whom emotional development does not proceed smoothly, placing the children at risk for poor cognitive, social, and behavioral outcomes, this policy paper paints a portrait of the kinds of young children and families who are in need of preventive, early intervention, or treatment services and offers relevant recommendations. The paper presents findings from research supporting why policymakers should invest in improving social and emotional health in young children, including the finding that achieving the national policy goal of school readiness for all children requires paying more strategic attention to early social, emotional, and behavioral challenges as well as cognitive and physical development. The paper next details a framework for action, noting objectives and characteristics of effective childhood mental health strategies as well as common elements of emerging service delivery strategies and initiatives. The paper then sets forth 10 action steps to move the agenda, including: developing state, community, and national strategies to ensure that healthy emotional development is integrated into the larger early childhood agenda; and addressing the key infrastructure and policy challenges, such as funding, serving young children who are at risk of developing and experiencing long-lasting emotional and behavioral problems, and building needed interagency collaborations. The paper's three appendices list: contact information for pertinent organizations; selected national organizations; and selected references for policymakers. (Contains 46 endnotes.) (HTH)