This study evaluates what and how personality traits (Big Five) of employees form their psychological contracts with respective employers. Therefore, apart from testing the direct relations between personality traits of employees and their psychological contracts towards employers, the present study investigates the ex planatory mechanisms (epistemic curiosity & rule-following behavior) between the Big Five personality traits and dimensions of psychological contracts, which in cludes transactional, relational, balanced and ideological contracts. In addition, the moderating role of individual level uncertainty avoidance is also examined in the relations between personality traits and explanatory mechanisms i.e. epistemic curiosity and rule-following behavior. Trait activation theory provides overarch ing theoretical framework for this study and norms of reciprocity offer additional support. Time-lagged data in three time-lags were collected from 469 respondents employed in various public and private sector organizations across Pakistan. Results indicate that Openness to Experience positively relates to transactional, balanced and ideological contracts and negative relates to relational contracts. Conscientiousness positively relates to transactional contracts and negatively re lates with relational, balanced and ideological contracts. The other personality dimension Extraversion positively relates to relational contracts and ideological contracts whereas it negatively relates to transactional contracts. Similarly, Agree ableness is found positively related with relational contracts and negatively with transactional and ideological contracts. Finally, Neuroticism negatively relates with all types of psychological contracts. Regarding explanatory paths, epistemic curiosity and rule-following behavior ex plain the relations between specific personality traits and psychological contracts as epistemic curiosity explains the relations between Openness to Experience, Con scientiousness and Extraversion and psychological contract types. While in case of rule-following behavior, majority of the hypotheses stand accepted, except for balanced contracts. In case of moderation, the results show that uncertainty avoid ance weakens relationship between Openness to Experience, Conscientiousness and x Extraversion and epistemic curiosity. The results regarding moderating role of uncertainty avoidance in the relations between Conscientiousness, Agreeableness, Neuroticism and rule-following behavior could only be partially claimed due to the fact that uncertainty avoidance was not found affecting the relation between Con scientiousness and rule-following behavior. Overall directions of buffering effects were somehow mixed as compared to expectations. These results have theoretical as well as practical significance. The study makes theoretical contribution in psychological contracts body of knowledge by adding two new explanatory mechanisms to elucidate the reasons why people with certain personality traits form different types of psychological contracts and what affect individual level uncertainty avoidance has on these relations. The practitioners can also benefit from these finding as they can ensure better expectations management and personality-job fit.