Although there are countless of supported literatures about the positive effect of leadership on project success, previous studies mostly focus on ‘’for-profit’’ organizations and do not try to evaluate whether or not the outcome would be similar in a non-profit organization. As non-profit organizations’ operations mainly depend on volunteerism, we aim to show the importance of this latter in the implementation and success of NGOs projects. The theoretical base adopted to better develop our model is the ProSocial Behavior (PSB). This study collected data from surveying 537 project development teams’ representatives worldwide including team leaders and volunteers from NGOs team operations. Using team identity and team climate as moderators, hypothesis were validated through Descriptive Data Analysis, Factor Analysis and Multiple Regression Analysis.
The results of our study indicate that servant leadership has a positive influence on volunteerism, team identity and team climate. They also show that volunteerism positively influences project success. Moreover, the results show that team identity is a significant moderator of the effect of servant leadership and volunteerism on project success, however team climate showed no significant moderation between servant leadership and project success.

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