The success of a Web 2.0 platform depends greatly on user-generated content. There are many “lurkers” who are willing to absorb knowledge but not to contribute to the virtual community. One of the challenges of Web 2.0 platform management is to manage Web 2.0 options such as the reach and richness of Web 2.0 processes and knowledge to encourage voluntary contribution on this interactive platform. The objective of this study is to investigate factors that affect users’ intentions of delurking and the moderating effects of Web 2.0 options on users’ knowledge-sharing behavior. The cognitive evaluation theory is applied in building factors that can possible affect users’ intentions to delurk. Factors such as perceived usefulness, community identification, altruism tendency, perceived enjoyment, and Web 2.0 self-efficacy were verified by frequent contributors of all types. Then, data from contributors of two major types of Web 2.0 platforms—experience-socialization platforms (N = 568) and intelligence-proliferation platforms (N = 694)—were collected, and motivators and moderators for delurking were compared. The results of this study showed that, for the contributors to experience-socialization platforms, the relative importance of community identification, altruism tendency, and Web 2.0 self-efficacy in the prediction of sharing intention varied when platforms possessed different levels of Web 2.0 options. On the other hand, for the contributors to intelligence-proliferation platforms, the relative importance of perceived usefulness, community identification, and perceived enjoyment in the prediction of intention varied when platforms possessed different levels of Web 2.0 options.