In this article we discuss the integration of international security assistance and rule of law promotion within larger state-building projects. Going beyond the widespread claim that both approaches should be closely linked within overarching security sector reform (SSR) efforts, this article inquires more systematically into their relationship both at a conceptual level and at the level of state-building practices. It argues that the creation of effective security institutions cannot be easily reconciled with programmes that promote mechanisms of legitimate political control as one dimension of the rule of law. Rationales behind security and rule of law support diverge: the former aims to strengthen a state's enforcement capacities, while the latter seeks to restrict them. The case of security and rule of law support to the Palestinian National Authority in the West Bank illustrates the tensions that can result. The article shows that in the Palestinian case, selectivity, fragmentation and timing issues have impeded the coherence of international assistance.