One of the first constatations for those researching populist parties is the lack of one, universal definition of the concept of populism. That reads directly into the ways we try to capture populist parties. Certain features unify the populist actors, primarily the supply of rhetoric to safeguard the majority rule of the people, by some referred to as populist ideology (Mudde, Kaltwasser, 2013). However, not only the definition of populism creates challenges to the proper identification of populist parties. Several other notions, such as ideology or left-right placement – and the misalignment in its general understanding – increase the complexity of studies that attempt to compare populist parties. The article focuses on theoretical aspects of populism studies, with a special focus on the populist parties in Central and Eastern Europe (CEE) that developed in a peculiar post-communist setting that influenced party performance in the region.