Previous studies have obtained divergent findings for the association between ethnic diversity and majority members' attitudes towards immigrants, suggesting that this relationship is moderated by individual or contextual difference variables. In a community sample of Dutch citizens (N = 399), we investigated the role of two potential moderators: right-wing authoritarianism and social threat in the local neighbourhood. Moreover, we assessed diversity and social threat in the neighbourhood with both subjective and objective measures. The results indicated that diversity was negatively related to positive attitudes towards immigrants among high authoritarians and among people experiencing their immediate environment as threatening. Conversely, diversity was positively related to out-group attitudes among low authoritarian individuals and among people residing in more secure neighbourhoods. The theoretical and practical implications of these person-environment and environment-environment interactions are discussed.