Background: Narcissism is characterized by entitlement, grandiose fantasies and the need for admiration. This personality trait has been associated with both traumatic experiences and emotional problems. Most studies have only focused on narcissism in the context of childhood trauma and negative emotional factors. However, dimensions of grandiose narcissism such as authority have been linked to adaptive outcomes. Furthermore, narcissism might not be linked only to negative childhood experiences; it may also be associated with the presence of post-traumatic symptoms. Therefore, the present study aimed to assess the associations between narcissism and the frequency and severity of post-traumatic symptoms and emotional factors (resilience capacity, emotional regulation, positive and negative affect, intolerance of uncertainty and perceived stress), as well as the possible mediational role of the latter in the relationship between narcissism and post-traumatic symptoms. Method: A total of 115 healthy young psychology undergraduates and their relatives, aged from 18 to 40 years, were asked to complete a set of questionnaires to evaluate the aforementioned variables. Results: The results showed that most of the grandiose narcissism dimensions were positively related to emotional adaptive outcomes, except exploitativeness and entitlement. The negative associations observed between the frequency and severity of post-traumatic symptoms and narcissism (self-sufficiency) were mediated by affect and resilience, which were in turn positively associated with the majority of the narcissism dimensions. Both positive affect and resilience were important factors mediating the association between grandiose narcissism and post-traumatic symptoms. Conclusions: Our findings reaffirm the need to assess not only desirable personality traits, but also ones that are not initially desirable, before pathologizing them. This consideration may be essential to achieve a personalized approach to the prevention of mental health problems, and promotion of positive emotions, in the general population.