This research note examines response and allocation rates for legal status questions asked in publicly available U.S. surveys to address worries that the legal status of immigrants cannot be reliably measured. Contrary to such notions, we find that immigrants' non-response rates to questions about legal status are typically not higher than non-response rates to other immigration-related questions, such as country of birth and year of immigration. Further exploration of two particular surveys – the Los Angeles Family and Neighborhood Survey (LAFANS) and the Survey of Income and Program Participation (SIPP) – reveals that these data sources produce profiles of the unauthorized immigrant population that compare favorably to independently estimated profiles. We also find in the case of the SIPP that the introduction of legal status questions does not appear to have an appreciable “chilling effect” on the subsequent survey participation of unauthorized immigrant respondents. Based on the results, we conclude that future data collection efforts should include questions about legal status to (1) improve models of immigrant incorporation; and (2) better position assimilation research to inform policy discussions.