Armed forces and security agencies are highly trusted national institutions. However, that does not make them unsusceptible to corruption. Even minor cases of corruption damage their reputation and impact their capacity to protect the country and people. If not curbed, corruption may permeate the fabric of security institutions and allow “state capture”. With this understanding, allies and NATO partners launched the Building Integrity (BI) initiative. This paper presents the activities of the Geneva Centre for the Democratic Control of Armed Forces (DCAF) in this initiative and the follow-up programme. DCAF's approach to the problem of corruption in security and defence organisations builds on an evolving body of knowledge and experience, setting BI activities in security sector governance and an institution building framework. The paper presents DCAF's approach, along with the statement that the key to the effectiveness of future counter-corruption efforts and sustainable international support is the collection and sharing of data and evidence on corruption in security and defence and the effectiveness of BI programmes.