The literature on migrants’ self-selection is focused on labour migrants, while little is known about refugees and internally displaced persons (IDPs). We contribute to this scant literature, by (1) examining a broad set of factors that could determine self-selection, (2) contrasting self-selection profiles of refugees and IDPs, and (3) comparing self-selection profiles of refugees across countries. Specifically, we compare the self-selection profiles of Ukrainian refugees and IDPs with stayers in the months directly following the Russian full-scale invasion in February 2022. We draw on unique, cross-nationally comparative data from the OneUA project, which surveyed Ukrainian refugees and displaced persons in Europe as well as those who stayed in Ukraine in the summer of 2022. More than 24,000 Ukrainian women residing in nine countries participated in this survey. We find systematic empirical patterns of self-selection related to people’s region of origin, family status, and individual-level characteristics.