• horizontal alliances;
  • transportation and logistics;
  • alliance complexity;
  • survey methods;
  • structural equation modeling

Various market challenges have led logistics service providers (LSPs) to engage in horizontal cooperations with each other, while maintaining their general legal independence. As an idiosyncrasy, horizontal cooperations entail the opposing forces of competition and cooperation, also referred to as “co-opetition” (Bengtsson and Kock 2000; Tsai 2002). This constellation facilitates the development of opportunism and conflicts, which raise the risk of relationship failure. Adequate governance mechanisms provide a basis to avoid failure and drive cooperation success. This paper focuses on the postformation cooperation management phase and identifies the specific effects that operational governance has on cooperation commitment and cooperation effectiveness. Based on survey data from 226 LSP cooperations, we show that both formal and social governance mechanisms have a substantial performance effect. In this regard, the results differ fundamentally from studies on vertical buyer-supplier relationships. With respect to the specific setup of the cooperation, a differentiated view is provided. Results indicate that two types of cooperation complexity are of relevance: organizational complexity and strategic complexity. The former drives the relevance of formal control; the latter increases the relevance of both formal and social control for cooperation success.