Tacit knowledge sharing discussed in this study is important in the area of business ethics, because an unwillingness to share knowledge that may hurt an organization's survival is seen as being seriously unethical. In the proposed model of this study, distributive justice, procedural justice, and cooperativeness influence tacit knowledge sharing indirectly via two mediators: organizational commitment and trust in co-workers. Accordingly, instrumental ties and expressive ties influence tacit knowledge sharing indirectly only via the mediation of trust in co-workers. The model is assessed by using data from different companies' employees, who attend an evening college in Taiwan for advance study. The test results of this study indicate that tacit knowledge sharing is affected by distributive justice, procedural justice, and cooperativeness indirectly via organizational commitment. Additionally, tacit knowledge sharing is also affected by distributive justice, instrumental ties, and expressive ties via trust in co-workers. The paths from procedural justice and cooperativeness to trust in co-workers are shown to be insignificant. Managerial implications of the empirical findings are also provided.