This article presents a descriptive theoretical-methodological model developed based on contemporary constructivist approaches to ethnicity research and situated within the context of the cognitive turn occurring in social sciences in general, and ethnicity studies in particular. This synthetic model addresses the question of what specifically needs to be researched when studying ethnicity and also provides tools for the operationalization of ethnicity for empirical research. Broadly, the model describes differentiating collective representations. The key elements of the model are ethnic categories and their relations, which are associated with various attributes divided into first and second-order attributes, also included in the model. The third type of elements in the model are general representations of the nature of ethnicity, characterizing the construction of ethnicity as a whole, understood as the entire collection of categories, attributes, and general representations in interrelation. The construction of ethnicity and its individual elements are the focus of empirical research, and the article also presents approaches to the operationalization of ethnicity within specific research designs. By accumulating contemporary approaches and distancing itself from other constructivist models (R. Brubaker, K. Chandra, A. Wimmer, and R. Jenkins), the article thus offers a transparent conceptualization of ethnicity, as well as concrete solutions for empirical research. It is addressed to researchers who, in one way or another, deal with ethnicity in their studies, yet lack a clear understanding of what exactly is being discussed when ethnicity is researched and what can be the focus of empirical investigations.