This paper examines empirically how multi-party networks can strive towards sustainable development. It investigates eight tourism networks in four European countries. All networks cross the private-public-sector borders involving business enterprises, authorities and, occasionally, citizen groups. Some networks focus on environmental sustainability, whereas for others sociocultural aspects of sustainability are more central. A special emphasis is laid on the SME perspective of these networks. The paper identifies a number of barriers and success factors of multi-party sustainability networks. Barriers include, for instance, conflicting goals, short-term thinking of participants or false expectations. Some of the key success factors included willingness of the members to invest in the network, the extensive expertise in the network and good contacts with important stakeholders outside the network. The findings indicate that sustainable development goals are interwoven with other personal, firm, regional or societal benefits provided by the network activity, and that such benefits have an important motivational role in the process in which sustainable development is implemented at a practical level.