In this qualitative study, James Oldham, assistant head of the Inclusion Advisory Service, Cambridge Education, and Julie Radford, senior lecturer in Special and Inclusive Education at the Institute of Education, University of London, investigate the tension in the role of mainstream secondary school SENCos. A review of legislation and literature concerning SENCo leadership has suggested that divergent forces are acting on the role, and in-depth interviews with SENCos in two local authorities were undertaken to gather data on this. It was found that SENCos consider leadership to be highly relevant to their role for reasons dominated by the team that they lead and the influence of more senior staff. Combined with little influence at a whole-school, universal level, it is suggested that this finding is evidence of divergent forces in operation. The distribution of leadership in schools and pressures regarding the achievement of pupils with special educational needs are proposed as causes and this is presented in a model. Potential problems emanating from this tension are explored and solutions are proposed for future consideration in theory and policy.