A Theory of the Microdynamics of Occurrent Thought (T2) is based on a reflective analysis of occurrent thoughts (OTs) in the spirit of phenomenological philosophy and proposes that such thoughts consist of a specific combination of ten or fewer micro phases possessing phenomenal contents that are so brief that most of us are unaware of their existence. The theory specifies the "movements" of an operating I or central executive in, as, and among these phases in the service of "processing" their contents by fleetingly "becoming" them, followed by one of several transitions of attention that bring about different degrees of their objectification. The relatively fixed sequences of the phases of OTs, along with an operating I's immersion in and "face-up" or "face-down" surfacing from their phenomenal contents, form a structure that carries and drives "on-line" cognition, supporting the view that they play a causal role in human information processing. Two categories, two forms, and fifteen different types of OTs are defined based on the transitions of an operating I therein. This book includes detailed illustrations of the different types of OTs.