The aim of this article is to introduce some theoretical frameworks which may develop the research going on within phenomenography and variation theory. Central concepts from the epistemological and cognitive theories of Charles S. Peirce, Niklas Luhmann and Margaret Boden are presented and their implications for phenomenography and variation theory are discussed. Peirce's concept of the semiotic triad clarifies the interrelations of conceptions, their linguistic expressions and their meanings or referents. Luhmann's concepts of primary and secondary distinctions point out an implicit hierarchy of dimensions of variation. Boden's notion of conceptual spaces as grounds for explorative and transformative creativity points to the relevance and value of becoming familiar with the conceptional spaces of the outcomes of phenomenographic studies. Finally, I point to the possibility of including the notion of a "hidden curriculum" of the discipline as an implicit dimension of variation in classroom studies based on variation theory. (Contains 1 table and 7 notes.)