The pharmaceutical industry is predominantly dominated by the handling of particulate matter in the form of solids and emulsions. With the enforcement of the Quality by Design (QbD) initiative by the Food and Drug Association (FDA), a process systems engineering based case toward particulate process design is advantageous. This suggests the need for mechanistic modeling approaches that can be used for an accurate representation of the process dynamics. The inherent discrete nature of population balance models (PBM) makes it an appropriate framework for modeling particulate processes. With the representation of the particulate processes used for pharmaceutical product manufacturing using various modeling frameworks, advancements can be made to improved control and optimization of the process. This chapter provides a detailed review on the applicability and significance of PBMs in drug product manufacturing and is aimed to provide greater insight into the field of process systems engineering.