Small and medium-sized enterprises (SMEs) are considered the backbone of the economy and often also a key engine of technological innovation and the creation of new employment. Despite of the fact that many SME support programs exist, especially to facilitate access to bank finance, and that the scope of these programs has been extended in response to the effects of the global financial crisis, small and innovative firms seem to continue facing a lack of sufficient external financing. This observation suggests that the design of existing support mechanisms such as especially credit guarantee schemes needs to be improved. The present article argues that the moment is opportune for OECD and EC member countries to adopt more structured approaches to the evaluations of costs and benefits of their SME support mechanisms, where they exist. Some guidance is available from an emerging academic literature that places a sharp focus on the design of a robust evaluation of this type of policy interventions. A survey of that literature suggests that the activities of CGS create both economic benefits and costs, and these – we argue – need to be more carefully weighed against each other.