This essay delineates the conceptual structure of cognitive linguistics and provides a reference framework for the other essays in this volume, which address and develop particular aspects of the theory. The two principal conceptual points emphasized by the author are the non-reducibility of linguistic expressions to truth conditions, and the predominant role played by perceptive, mental and even motor conceptualization in natural language. The essay concentrates in particular on the main forms of construal, or the ability to conceive and portray the same situation in alternate ways (through specificity, different mental scanning, directionality, vantage point, figure-background).