The goal of the present research was to investigate the effects on comprehension and inference-making when prior knowledge about a building was manipulated by means of a text. The text presented an expert-like "walk- through" description of the building, as well as exemplars of the eight types of semantic information previously fovmd to be employed in the comprehension of architectural plans. This was motivated by previous research which: 1) found that the nature of the encoding process is related to both specific prior knowledge of the building and to expertise, and 2) suggested that experts' representations of the building included much more 3-dimensional infonnation whereas sub-experts' representations of the building were much more similar to the 2- dimensional plans used to depict the building. Results indicated that the text had positive effects on specific types of semantic information acquired about the building, and that inferences on this information permitted the development of mental models which included a greater number of 3-dimensional aspects of the building. There were also important findings related to expertise which suggest that the search, pattern-recognition, and inference-making operators applied by novices were different from those applied by experts.