Many culturally-plural societies like Canada or Russia seek ways to manage their cultural diversity in order to promote harmony among coexisting groups. The social sciences have long viewed intergroup contact as a beneficial intervention to achieve such harmony. This paper proposes an adaptationist framework within which to explain how and why intergroup contact contributes to the positive and negative outcomes for individuals who live together in a plural society. We employed this framework in a case study that may serve as an example of the conceptualization and analysis of these issues in international research. Its structural framework included both positive and negative contact and the role of this contact in the distribution of intercultural and psychological adaptation among a large representative sample of the Canadian population. We used a correlational design with a representative sample of Canadians from a survey carried out by Environics in 2019, which was stratified according to the most current population statistics. The total sample was 3,111 persons age 18 and over and included the largest racialised groups in the country. Our main finding was that intergroup contact (both positive and negative) related to both psychological and intercultural adaptation. These findings have implications for improving intercultural relations, especially through the role of positive contact. The experience of negative contact (e.g., discrimination) in the near term is an important factor in undermining both forms of adaptation. Nonetheless, while intergroup contact can bring both positive and negative experiences during intercultural interactions, it leads to mutual adaptation over time.