Although immigration is one of key issues facing European societies today, many survey respondents do not reply to questions about immigration and ethnic minorities. Using data from the 2014 European Social Survey, this paper explores the characteristics of nonrespondents and the potential mechanisms which might lie behind their refraining from answering immigration-related questions. Item nonresponse to seven questions on the impact of immigration (impact items) and six questions on allowing ethnic/racial/religious minorities into the respondent's country (openness items) is analysed. The results indicate that nonresponse to these items is systematically related to respondents' profiles, their experiences, the characteristics of the interviewer, and the country context. Respondents with a moderate amount of contact with ethnic minorities and who are interested in politics are least uncertain about their attitudes and most likely to report them. Contrary to expectations, nonresponse is not lowest among the more educated – indeed, the nonresponse rate for the openness items is highest for the most highly educated. The results also point to the importance of the interviewer effect, as nonresponse to immigration-related items varies more between interviewers than between countries. The paper concludes by highlighting the implications for the design and analysis of surveys measuring attitudes towards immigration. [ABSTRACT FROM AUTHOR]