The market in which firms compete magnifies the need for buying firms to effectively manage and develop their supply chain. One of the important notions in the management and development of the supply chain is the implementation of supplier development program. Previous extensive literature review has identified various types of activity in the supplier development program, which categorized as low involvement activity to high involvement activity. Further, extensive literatures on supplier development program implementation and its implication on supplier's capability are also available. However, there is still limited empirical research for investigating the determinants of knowledge sharing effectiveness in supplier development programs. Aimed at bridging that gap, this study attempts to investigating the role of supplier's organizational culture, information and communication technology (ICT), and perceived behavioral control as the determinants of knowledge sharing effectiveness by mentorship in the supplier development program (SD). A survey questionnaire was employed to collect data from 200 suppliers after conducting mentorship training at the suppliers' site. The data were analyzed using bootstrap resampling method (with 5,000 resamples). The bootstrap samples are used to estimate the Partial Least Square (PLS) path model. The results of path analysis indicated that all variables are significantly associated with knowledge sharing effectiveness with mentoring mechanism (p-values<0.05) except collaborative culture to knowledge sharing effectiveness which was insignificant. It was also observed that ICT and perceived behavioral control affected the effectiveness of knowledge sharing by mentorship in the SD program. INDEX TERMS Supplier development, knowledge sharing, mentorship.