This study investigates the establishment of voluntary inter-organizational IT governance between healthcare and social welfare organizations. Special attention is placed on the role of perceived IT cooperation benefits, a novel factor introduced in this research. First, IT governance research, the resource based view (RBV), transaction cost economics (TCE) and social psychology theories are discussed as the theoretical background of perceived IT cooperation benefits. In the case benefits were operationalized to concrete level statements and evaluated with an expert survey. Survey results and the statements were eventually used to justify a proposed IT governance arrangement engaging over 100 organizations. Empirical results revealed that the perceived IT cooperation benefits had a decisive role both in the commitment to prepare the proposal and in the acceptance and implementation of the proposal. Positive expectations regarding IT cooperation benefits were able to outweigh the negative trust issues which had resulted partly from previous failures to establish comparable arrangements. In the survey operationalized IT cooperation benefits were evaluated to be highly significant for the proposed arrangement. Variations in evaluations were unrelated to demographic, situational or behavioral variables.