Developed by Gilles Fauconnier and Mark Turner, blending theory derives from two traditions within cognitive semantics : Conceptual Metaphor Theory and mental spaces theory. Blending theory holds that meaning construction involves integration of structure that gives rise to more than the sum of its parts. The mechanism that facilitates this, known as conceptual integration or 'blending', is held to be a general and basic cognitive operation which is central to the way we think. In terms of its architecture, and in terms of its central concerns, blending theory is most closely related to mental spaces theory, not least due to its use of mental spaces and mental space construction as a key part of its architecture. However, blending theory is a distinct theory that has been developed to account for phenomena that mental spaces theory, and indeed conceptual metaphor theory, cannot adequately account for. Moreover, blending theory adds significant theoretical sophistication of its own.

Blending theory was originally developed in order to account for the role of language in meaning construction, particularly 'creative' aspects of meaning construction like novel metaphors, counterfactuals and so on. However, recent research has given rise to the view that conceptual blending is central to human thought and imagination, and that evidence for this can be found not only in human language, but also in a wide range of other areas of human activity. In particular, Fauconnier and Turner argue that the ability to perform conceptual integration or blending may have been the key mechanism in facilitating the development of advanced human behaviours that rely on complex symbolic abilities. These include rituals, art, tool manufacture and use, and the development of language.