Longitudinal Surveys for Comparative Analyses of Poland and Romania: The Polish Panel Survey (POLPAN), 2013–2018 and the Romanian World Values Survey Panel (WVS-RO), 2012–2018

: If researchers wish to use surveys to understand the attitudes and behaviors of those who live in former State Socialist countries, they face a research landscape densely populated by cross-sectional studies. Panel surveys with individuals as the units of analysis, which are ideal for understanding change within people over time, are rare. As a service to researchers, this article presents possibilities for cross-national comparison via two sets publicly available panel data: the Polish Panel Survey POLPAN (focusing on its 2013 and 2018 waves) and the novel Romanian World Values Survey Panel RO-WVS (2012 and 2018 waves), which is the only panel version of World Values Survey (WVS). We present the research designs of each, and explore their ex-post harmonization. Conceptual overlap between these sources occurs mainly (but not only) with major socio-demographics and with political attitudes and behavior, including interest in politics, political participation, democratic values, and institutional trust. Whereas POLPAN is relatively well known, we argue that RO-WVS panel stands out as a unique resource that provides data on the