This article examines the formation process of spatial presence, which is conceived as a two-step process involving the construction of a mental model of the mediated environment, followed by the emergence of spatial presence. During both stages, cognitive processes and user traits are in effect. We present data derived from a pooled set of data of three studies using the same virtual environment. Structural equation modeling is used to confirm the proposed theoretical model. The results show that attention and the trait of visual spatial imagery are positive predictors of the mental model of the mediated environment. In the second step, the formation of spatial presence is governed by involvement, the suspension of disbelief, and the domain-specific interest, together with the mental model.