Migrants are a diverse and potentially disadvantaged minority group which makes them hard-to-reach and hard-to-survey. As migrant research often relies on general population survey studies, it is important to understand the potential consequences of these surveys shifting from traditional face-to-face to mixed-mode interviews for the composition of migrant samples. By comparing the Austrian segment of the European Social Survey (ESS) and the Social Survey Austria (SSA) to the official Austrian microcensus (MZ) from the years 2016 to 2023, we find that shares of respondents with a migration backgrounds are significantly lower in both social surveys, irrespective of data collection mode. …