With the increased importance of groupware in organizations, groupware acceptance is regarded as an important outcome in the efforts of firms to leverage the potential of this information technology in their business activities and strategies. Despite significant investments in groupware, considerable diversity exists in how well firms have been able to implement groupware and leverage the business value of groupware. This study identifies important factors influencing user acceptance of groupware by extending TAM(Technology Acceptance Model) which includes perceived control, intrinsic motivation, and concentration as well as perceived ease of use and perceived usefulness from original TAM. The proposed model is tested in an organization among 104 employees using previous research measurements. According to the findings from the study, the usage intention of groupware can be explained by intrinsic motivation, perceived control, perceived ease of use, and Perceived usefulness. However, it fails to explain the effect of concentration on the intention.