This literature review examines the research on early childhood education and care (ECEC) leadership and how leaders impact process quality in ECEC settings. Process quality refers to interactions and relationships between and among children and ECEC staff, and is a strong predictor of children's learning, development and well-being. Research suggests that leadership plays a central role in improving and sustaining process quality in ECEC settings. This literature review presents findings about: (1) the functions, roles and structures of leadership in ECEC settings; (2) factors that may support or hinder leadership and its effectiveness; (3) working conditions and professional development for staff; and (4) how these factors might impact process quality. The results suggest that supports for ECEC leadership may be needed to strengthen areas such as leadership recruitment, preparation and professional development, credentialing and compensation, job design and further research.