Romania is home to the largest Roma population in Europe. Exactly how large is a matter of intense debate, with estimates ranging between 0.62 and 1.85 million. The last Romanian census made the ethnic affiliation question unequivocally optional and it counted 1.24 million citizens with undeclared ethnicity, a huge increase from the 1941 cases recorded by the previous census round. Since the Roma are the only ethnic group expected to avoid disclosing ethnic affiliation, previous analyses of this idiosyncratic result attributed it exclusively to Roma discrimination led reticence. The current article corrects this view by analyzing the important role played by a previously ignored methodological change (i.e. recording as 'undeclared' the temporary absent citizens for whom their neighbors could not provide any information about ethnic affiliation) and revealing that lack of information about neighbors played a dominant role in urban municipalities.