An objective of Singapore’s ongoing public sector reform (PS21) requires agencies to focus on getting the best out of its employees. One way of doing this is by creating a positive leader–member exchange (LMX) relationship, enabling supervisors to motivate their subordinates towards the development of organizational citizenship behaviours (OCBs). This article reports the extent of LMX and relational quality in a public sector agency experiencing PS21 reform and high staff turnover. In addition, we examined the effects of organizational justice perceptions and job satisfaction towards a subordinates’ OCB. A path model was developed to examine the relationships between LMX, organizational justice, job satisfaction, and OCB and tested by applying LMX theory. The path analysis results showed that LMX mediates the relationship between organizational justice perceptions and OCB. The results also showed that one’s job satisfaction led to higher level of OCB. The study findings have implications for theory and practice which have been presented in the discussion section.