This paper is concerned with the operation of professional networks, norms and trust for leadership in interprofessional relationships and cultures and so the analytic of social capital is used. A mapping is outlined of the sub-types, forms and conceptual key terms in social capital theory that is then applied to explore and better understand interprofessional leadership resources and relationships. Since policy statements cite leadership as a principal mechanism for mediating co-working, concepts of leadership and some of the tensions and difficulties in its current conceptualizations and operations are identified. These are analysed in relation to policy and practice governing different children's services professions and subject disciplines, here exemplified by education and health in a Scottish context. (Contains 1 table.)