The current study tested assumptions derived from the whole‐trait theory (Fleeson, 2012), which proposes a connection between personality and motivation. We hypothesized that individual differences in social approach and avoidance motives are associated with personality as observed by others. In addition, we expected that observed personality links social approach and avoidance motives to interpersonal outcomes. The sample was composed of 83 young adults (25.3% males, Mage = 21.66 years) who had recently moved into a shared apartment. Roommates (N = 83; 50.6% males, Mage = 22.83 years) evaluated the newcomers on Extraversion, Agreeableness, and likeability. Approach motives had an indirect positive effect on likeability through other‐reported Extraversion and Agreeableness. Although avoidance motives had some negative effects on likeability mediated through low Extraversion, they were positively associated with Agreeableness. These results demonstrate the complexity of social approach and avoidance motives. Moreover, they highlight the importance of motivational factors for observed personality.