European small- and medium-sized businesses (SMEs) are the backbone of the European economy. SMEs account for well over 90% of all European enterprises, provide two thirds of overall employment and in recent years have been the most active providers of new jobs. For these reasons, the vitality of the SME sector is a prime concern of policy makers at EU level, in the Member States and in the EU regions. Although a large amount of funds is invested at European, national and regional levels for SME support, the benefits of interregional benchmarking and policy learning are not yet fully explored. The operation "Eurochallenge - European support system for international co-operations of SMEs" focuses on creating joint benchmarks and instruments to measure the effectiveness of existing services to SMEs. It also aims to upgrade existing policy instruments, establish synergies among support schemes and improve the competitiveness of SMEs through partner matching services and SME support plans. transparency of SME-support systems in the partner regions. The operation also enhances capacities to measure the effectiveness regional action plans for SME-partnerships and of Structural Funds spent on SME-support. Activities include the creation of tailor- made interregional support models for SME- co-operations and the development of an evaluation instrument for public authorities. Partners actively involve decision makers in the strategic and content-related project issues to ensure durability of results and increase awareness among public authorities. Lessons learned are published in the form of guidelines for SME-cooperation and a handbook for policy makers on effective SME-support.