This article develops a theoretical model about the trajectories and transitions of thought from a perspective of semiotic cultural psychology. An integration between the inner speech theory, concept formation, and dialogical self theory was done to explore the particularity of thought transitions. It is concluded that the thought transits in a vertical and horizontal axis-from an irrevocable past to an uncertain future and from the lower levels of consciousness to the higher levels of thought-determined by the nature of inner speech-structural and semantic-the quality of concept formation process and the different dialogical relationships that occur between the I-positions of the self. It is proposed that it is these dynamics of thought that make it an idiosyncratic, historical, and genetic phenomenon, which makes empirical approaches difficult and influences theorizing about the thinking process.