The mathematical thinking and acting of learners are determined by individual interpretations of mathematical concepts. These interpretations can be reconstructed from an individual perspective––as individual conceptions––as well as from an interactionist perspective––as specific frames. So far, however, it remains unclear, how individual conceptions take effect in mathematical interactions and, on the other hand, how joint negotiation processes about mathematics affect the development of sustainable individual conceptions. Combining both concepts, we develop the concept of individual conception frames in order to create a theoretical foundation for the empirical analysis of individual mathematical learning in interactions.