Consultation has become a primary strategy in Head Start and Early Head Start mental health services for promoting the mental health of young children and families as well as preventing and reducing the impact of troubling or challenging behavior. Concurrent with the evolution of mental health services in HS/EHS, the last 10 years have brought significant influence to the understanding and implementation of early childhood mental health consultation. The significant landmarks on this timeline include defining early childhood mental health consultation, establishing the evidence base that consultation works, determining factors that contribute to effective consultation, and building the capacity of states and communities to deliver and evaluate ECMHC services.