This pilot study aims to assess the predictors of knowledge workers’ attitude toward inter-organizational knowledge sharing system (IOKSS) in horizontally-linked organizations. Even though IOKSS may encounter several organizational and individual challenges, their deployment in knowledge-intensive sectors can be valuable and crucial for effective social and economic development especially in developing countries. Knowledge workers’ attitude toward IOKSS is critical as they are the driving force of such systems; IOKSS can only survive through their commitment and use. However, prior research on inter-organizational systems (IOS) system has focused on organizational adoption, and mainly on vertically-linked organizations. Based on data collected from school teachers in organizations in the education sector, this study indicated that several factors related to individual, peers, proposed IOKSS, the organization are significantly contribute to knowledge workers’ attitude toward IOKSS. Such results can provide several insights for researchers and practitioners on their adoption of IOKSS.