In this study we examined how specific personality traits are related to psychosocial adjustment in people with intellectual disability. We studied 73 students with mild intellectual disability and 25 students with moderate intellectual disability who attended special schools in Poland. Personality traits were assessed with the Revised Edward Zigler-Yale Questionnaire (EZPQ-16R) and to assess adjustment we used a total-difficulties score in Strengths and Difficulties Questionnaire (SDQ). We hypothesized a predictive relationship between the specific personality traits and adjustment. The relation between personality and adjustment was stronger in people with moderate intellectual disability than in people with mild intellectual disability. In students with moderate intellectual disability the relation between personality and adjustment was significant for each of the studied traits and in students with mild intellectual disability it was significant for negative-reaction tendency, and assignment alacrity. Obtained results indicate that specific traits are important to adjustment of people with intellectual disability.