Security sector reform (SSR) is a concept that is highly visible within policy and practice circles and that increasingly shapes international programmes for development assistance, security co-operation and democracy promotion. This paper examines the concept and practice of SSR using theories of the state and state formation within a historical-philosophical perspective. The paper recognises that the processes of SSR are highly laudable and present great steps forward towards more holistic conceptions of security and international development. However, the main argument of the paper is that we should be careful of having too high expectations of the possibility of SSR fulfilling its ambitious goals of creating states that are both stable and democratic and accountable. Instead, we should carefully determine what level of ambition is realistic for each specific project depending on local circumstances. A further argument of this paper is that legitimate order and functioning state structures are prerequisites and preconditions for successful democratisation and accountability reforms within the security sector.