Over the course of almost three decades, Russia has led the development of a number of multilateral organisations, aimed at political, economic and security cooperation with those former Soviet states willing to engage in Moscow-led projects. The primary security project is the Collective Security Treaty Organisation (CSTO). The decision by the other former Soviet states to take up membership, or not, in the CSTO is commonly considered as indicative of their wider geopolitical orientation, as either more pro-Russian or pro-Western. However, another relevant rationale for membership is political-economic. There are significant financial and resource incentives on offer for joining the CSTO, provided by way of Russia’s disproportionate contribution to the organisation’s budget and the provision of hardware at below market rates to membership. Taking this into account, this chapter examines the CSTO’s budget and maps the financial politics of membership, in order to establish whether this perspective provides a better account for its development than solely geopolitical identity.