The decision of members in a knowledge-intensive team to withhold their knowledge may threaten the performance of the team. To address the problem of knowledge resource risk in project teams, we maintain that it is important to understand why team members choose to withhold their knowledge, conceptualized as knowledge-withholding intention. In line with the literature on effort withholding, the research on multifoci relations between justice perceptions and social exchanges, and social cognitive theory, we proposed that the social exchange relationships that individuals form in the workplace, their perceptions of justice, and their knowledge withholding self-efficacy would influence their knowledgewithholding intentions. Through a survey of 227 information system development team workers, we found that all social exchange relationship variables had a significant impact on knowledge-withholding intentions. However, the justice perception variables only indirectly influenced knowledge-withholding intentions through the mediation of social exchange relationships. In addition, one of the task variables, task interdependence, influenced knowledge withholding intention through the mediation of knowledge withholding self-efficacy. Our results contribute to the knowledge management literature by providing a better understanding of the antecedents of knowledge withholding. We also offer suggestions for future research utilizing the framework of Kidwell and Bennett (1993) to study effort and knowledge withholding.Keywords: Knowledge-withholding intentions, information system development team, organizational justice, social cognitive theory, social exchange theory Abbreviations: AVE, average variance extracted; CFI, comparative fit index; DJ, distributive justice; IJ, interactional justice; ISD, information system development; KWI, knowledge-withholding intentions; KWSE, knowledge withholding self-efficacy; LMX, leader-member exchange; MIS, management information systems; PJ, procedural justice; POS, perceived organizational support; RMSEA, root mean square error of approximation; SCT, social cognitive theory; SEM, structural equation modeling; SET, A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 3 social exchange theory; SRMR, standardized root mean square residual; TI, task interdependence; TV, task visibility; TMX, team-member exchange.