While the concepts of language continuum and diglossia are widely cited and discussed, they remain generally vague and are used in different ways by different linguists. Recent sociolinguistic research on Dutch-speaking Belgium provides a framework for examining the two concepts, a context for proposing a theoretical definition for language continuum, and a context for examining Fasold's distinction between "broad" and "leaky" diglossia. Results of a macrosociolinguistic study of language behavior in two western Flemish towns lead to the conclusion that, at least in the mind of the language users, there is no language continuum in the common sense of the term, and the situation is diglossic. Information gathered in such macrological research requires the complementary micrological research in order to be complete, but macrological studies are also necessary to establish the specific needs for micrological research. (MSE)