Two studies investigated the mediating roles of self-motivated behavior (self-efficacy, self-interest and learning behavior) in accounting for the influence of intergroup member contact for intergroup harmony. In study 1, seventy-six (males = 55.26%; females = 44.74%) freshmen students, age ranged between 16 and 25, (M = 22.54, SD = 4.45) years voluntarily participated. Cross-sectional design with regression analysis revealed that intergroup contact significantly predicted intergroup harmony. In study 2, one hundred and two students (males = 56.2%); females = 43.8%) freshmen (100 level) of ethnic origin (Igbo = 45.6%; Hausa/Fulani = 20.4%; Yoruba = 24.5% & others = 9.5%); religious orientations (Christians = 62%; Muslim = 38%) age ranged between 17 and 26, (M = 22.15, SD = 2.35) years, voluntarily participated. Cross-sectional design which adopted regression analysis showed significant positive indirect effect of intergroup member contact on intergroup harmony through self-efficacy, self-interest and learning behaviour. The outcome of the study suggested for the first time a framework for understanding the roles of self-motivated behavior in intergroup member contact’s effect for intergroup harmony. The study results highlighted the need to consider self-motivated behavior in developing social interventions for peace building and intergroup harmony in multi-ethnic nation.