In toady’s competitive markets, tacit knowledge has become an important source of competitive advantage for firms. Building on TCT theory, this study investigates the effect of contractual completeness on the acquisition of tacit knowledge, and the moderating role of competition intensity and procedural fairness. Results from a sample of 196 R&D alliances in China demonstrate that contractual completeness has an inverted U-shaped relationship with acquisition of tacit knowledge. In addition, this study finds that the inverted U-shaped relationship between contractual completeness and tacit knowledge acquisition is weaker when competition intensity is high, while the impact of contractual completeness on tacit knowledge acquisition is not influenced by procedural fairness.