Objectives: To describe how funds were pooled or otherwise jointly managed by National Health Service (NHS) primary care trusts and local authorities in England. To compare expenditure on local children's services by health, education and social services. Methods: We conducted a questionnaire survey of all 35 children's trust pathfinders, six months after they were launched, with a follow-up at 2.5 years. We also undertook an in-depth analysis of local authorities and primary care trusts, within eight pathfinder areas and three non-pathfinder areas, whereby we compared expenditure on children's services, interviewed managers and professionals and examined financial documents. Results: Local authorities and NHS trusts coordinated expenditure in various ways, most commonly through informal agreements and aligning budgets but also by formally pooling budgets. The latter were usually for selected services such as child and adolescent mental health services, though four children's trusts pathfinders pooled (or aligned) their budgets for all children's services. Total expenditure per child was greatest for education, lowest for social services and intermediate for health. However, it was difficult to quantify education expenditure on children with health and social care needs, and health care expenditure on children. Conclusions: Sharing money for local children's services requires shared objectives, trust, and legal and accounting expertise. Several different mechanisms are permitted and many are feasible but programme budgeting for children's services could make them more effective.