This study investigates the perceptions and practices of early childhood practitioners in relation to the development of thinking in children aged 3-5 years. Five practitioners working in nursery and reception classes in England were interviewed, and sessions were observed in each setting, including discussions with the children. The results suggest that these practitioners believe that supporting the development of young children's thinking is an important part of their role, but that it often remains an implicit rather than explicit part of their planning. A range of contexts was cited by practitioners as supportive of the development of children's thinking, and emphasis was placed on children's own choices, sufficient time to carry out child-chosen activity, and opportunities for talk. Views were divided about the impact of the curriculum guidance for the foundation stage, and there were some differences in the views of practitioners between the nursery (3-4 years) and reception (4-5 years) age groups.