This article explores different measurements of (sub-)national identities in survey research and examines to which extent they lead to different results. Using survey data from Belgium, where there is a long-standing tradition of (sub-)national identity surveys, three types of questions are scrutinized: the ‘hierarchical’ question (asking respondents to which of a list of given identities they feel most closely related in first and second place), the ‘Linz-Moreno’ question (asking respondents to situate their regional and national identity vis-à-vis of each other) and the more recent ‘metric’ question (asking respondents to situate themselves for multiple identities on distinct 11-point scales). This article analyses the extent to which respondents answer these questions consistently, how varying degrees of consistency can be explained and what this tells us about the way social scientists measure (sub-)national identities. The results show that, depending on the question, only 39,4% to 69,2% of the respondents answer the three (sub-)national identity questions consistently. Differences in consistency are found to be not only related to respondents’ political knowledge and interest, but also to the question forms and wordings, obliging us to reflect on the validity of identity measurements. ; This article explores different measurements of (sub-)national identities in survey research and examines to which extent they lead to different results. Using survey data from Belgium, where there is a long-standing tradition of (sub-)national identity surveys, three types of questions are scrutinized: the ‘hierarchical’ question (asking respondents to which of a list of given identities they feel most closely related in first and second place), the ‘Linz-Moreno’ question (asking respondents to situate their regional and national identity vis-à-vis of each other) and the more recent ‘metric’ question (asking respondents to situate themselves for multiple identities on distinct 11-point scales). This article analyses the ...