This study examines the relationship between ethnic diversity and social trust, and whether the relationship between the two differs according to political affiliation among young adults. Two hypotheses were tested based on the literature on trust, ethnic diversity, and political party preferences. In addition, data from the SOM-institute’s 2020 annual survey is analyzed together with data from Statistics Sweden on population composition, which divides the population into domestic and foreign-born in Sweden’s municipalities using regression analyses. However, the study finds no support for the research question that young adults who lives in ethnic heterogeneous municipalities have lower trust than those who live in homogeneous municipalities. The initial bivariate regression shows a positive relationship between the two, but not a statistically significant result. In line with previous research, control variables such as education level have a positive relationship with social trust. Moreover, the study finds a negative relationship between government voters and social trust. The results do not indicate any support for the second research question that the relationship between increased ethnic diversity and social trust differs according to political affiliation among young adults.