In this paper, I draw on the growing body of work in surveillance studies, to examine the increasing propensity in recent years towards the monitoring and collection of information about children's weight and health within school contexts. Applying Haggerty and Ericson's concept of the surveillant assemblage within school contexts, the paper examines how surveillant practices in schools are part of an assemblage constituted by a range of agencies, institutions and bodies, and socio-technological developments constituted through a complex series of rhizomatic flows. (Contains 4 notes.)