This paper addresses the broad question of whether or not the UK SEN system works from the perspective of the parent and the child, at the moment when a need first becomes apparent. The sparse literature on this topic suggests parental experiences may differ substantially, but there is growing evidence from small-scale studies that parents are unhappy with the situation and children's needs are not being met. The findings of a longitudinal participant observation study are presented. It is argued that current conceptualisations of the SEN system are located exclusively or primarily within the educational domain and fail to take into account the full complexity of the system. To access support via the SEN system, a child and his/her parents have to interact within three distinct domains: educational, legal and medical, and in each of which the child occupies a qualitatively different space as "pupil", "case" and "patient". There is scope for errors and failings to occur within each domain, at multiple levels, and in the interstices between domains. Furthermore, at all levels, the system has both formal and informal dimensions. We argue that this alternative "whole systems" perspective on the SEN system transcends current conceptualisations and that existing "solutions" proposed to improve the SEN system will not work unless they take into account these complex dynamics. (Contains 1 table and 1 figure.)