In the original theory of group performance in software development technical reviews there was no consideration given to the influence of the inspection process, inspection performance, or the inspected artifact, on the structure of the theoretical model. this paper presents an extended theoretical model, along with discussion and justification for components of the new model. These extensions include consideration of the software product quality attributes, the prescriptive processes now developed for reviews, and a more detailed consideration of the technical and non-technical characteristics of the inspectors. In this paper we present both the structure of the model and the nature of the interactions between elements in the model. Consideration is also given to the opportunity for increased formalism in the technical review process. We show that opportunity exists to both improve industrial practice and extend research-based knowledge of the technical review process and context.