Objective: In this study, the effect of personality on perceived social support, loneliness, social network and negative social relationship were assessed. The predictive role of personality on social network, loneliness and social support was investigated. Methods: Two hundred and twenty-five subjects were assessed with Temperament and Character Inventory, Multidimensional Scale of Perceived Social Support, UCLA Loneliness Scale, Social Network Inventory and Negative Social Relationship Question. Results: According to regression analysis, self-directedness and self-transcendence predicted social support, and self-directedness, harm avoidance, persistence and self-transcendence predicted loneliness. Path analysis results indicated that social support, loneliness and social network have a partial mediator effect on this predictive relation. Conclusion: Results were discussed according to Cognitive Bias Model and Social Network Mediator Model. [Anadolu Psikiyatri Derg 2013; 14(1.000): 46-52]