The attempt to derive design innovations from social science theory proved successful in motivating online community contributions. Study 1 demonstrated that emails emphasizing the uniqueness of potential contributions increased movie ratings more effectively than messages emphasizing commonality or benefit. Study 2 results contradicted the collective effort model by revealing that participants exerted more effort when in groups rather than when individually identified. Ultimately, mining social science theory serves as a useful general strategy for the design of computer-supported cooperative work (CSCW) systems. When interventions fail to increase contributions, researchers identify three possible classes of explanations: failures of implementation, mismatches between engineering and scientific disciplines, and incomplete theories.