This paper analyzes the evolution of Walloon and Flemish citizens in relation to various ethno-territorial political entities in Belgium during the period 1979–“2004. Using multiple forms of operationalization (the Moreno Question and hierarchical intensity and frequency of feeling of belonging), we note a gradual process of identification with Belgium among the Walloon electorate, while in Flanders, the evolution is curvilinear, even though the sense of belonging has been greater toward Belgium than toward Flanders since the 1990s. We estimate the strengths and weaknesses of each approach, and we identify other methodological problems in research on identities.