Historically application of mechanistic modeling approaches to processing steps in pharmaceutical oral solid dosage form manufacturing have been limited compared to similar efforts for small molecule synthesis. One plausible explanation may be that there has been a lack of fundamental governing equations for drug product processes. The general similarity of oral solid dosage form processes from product to product make models in this area highly reusable and they can be used for purposes such as reducing scale-up and technology transfer times as well as reducing material usage for these activities. In this chapter we describe three mechanistic models used in oral solid dosage form process development and manufacturing from the perspective of how they are developed, used, and linked with supporting empirical data. The three models cover fluid bed granulation, tablet coating, and spray drying. The focus of the chapter is to illustrate the importance of embedding the models into existing development, scale-up, and manufacturing workstreams such as to create a model enhanced workstream that is more efficient, faster, and better routed in science than the fully empirical approach. Such workstreams require verification of their performance before being fully operational which is also discussed.