This paper presents a theoretical exploration of generalization and abstraction as processes of mathematical thinking. After presenting an overview of the mathematics education literature on generalization and abstraction, we highlight the principal characteristics of these two processes. Based on the commognitive framework, we situate generalization and abstraction as discursive processes. The first generates new utterances that extend an existing discourse. The second creates a new discourse with its own rules and new objects that are not coherent with the old ones. We conclude with how they might be related to mathematical reasoning, and thereby propose that abstraction not be considered a process ofmathematical reasoning.