Noting that most individuals working with young children and their families lack the knowledge and skills to identify early warning signs of significant child distress and that most communities lack resources and expertise to address early social and emotional concerns, this report discusses the importance of healthy social and emotional development and describes the emerging field of early childhood mental health in Illinois. The report asserts that a childs earliest relationships and experiences contribute significantly to brain development and identifies environmental conditions and experiences that place young children at risk for emotional or behavioral difficulties. Behaviors of infants and toddlers and of preschoolers signaling child distress are delineated. The report further describes findings of a study of the effects of maternal depression on the young child. The report then describes three levels of early childhood mental health strategies: (1) promotion of nurturing and responsive caregiving, including periodic screening for emotional and behavioral concerns; (2) prevention of social/emotional problems for children facing constitutional or environmental risks; and (3) targeted intervention for families displaying a disturbed parent-child relationship or for children whose emotional development deviates significantly from typical behavior. The report describes the role of early childhood mental health specialists in consulting with early childhood program staff to incorporate promotion and prevention strategies into their work and that of specialists with clinical training to provide targeted intervention. The practice of early childhood mental health in one Illinois county is described. The report concludes by urging state agencies, policymakers, early childhood professionals, advocates, and families to make the social and emotional well-being of infants and young children a top priority and delineating ways to build a systemic approach to provide early childhood mental health services. (Contains 10 endnotes.) (KB)