Based on the negative outcomes of international organisations trying to stabilise failing states, this study analyses the chances of success of international missions in acting preventively in so-called weak states. It therefore focuses on the OSCE’s missions in Kyrgyzstan and Tajikistan, which for almost 20 years aimed to stabilise both countries. Using a strongly refined version of Schneckener’s model of fragile statehood, the study analyses the efforts of the OSCE to foster the three state functions of security, welfare and legitimacy/rule of law in both countries. It devotes particular attention to the OSCE’s dilemma of balancing effective work with not infringing on national sovereignty, which is de facto impossible with regard to fighting corruption. Finally, the study discusses three strategies in dealing with this dilemma.