This chapter focuses on process-intensified design methods. Furthermore, it clarifies the differences between conventional process design based on established predefined unit operations and design based on process-intensified principles. Process intensification (PI) design methods are not only suited for new processes but also for retrofitting and revamping existing processes. Special attention is paid to this subject and opportunities to apply PI are shown. PI is a set of radically innovative process-design principles which can bring significant benefits in terms of efficiency, cost, product quality, safety, and health over conventional process designs, when compared with designs based on established unit operations. All PI design methods can be classified into five domains: spatial plant-wide, functional synergy, temporal, thermodynamic, and spatial equipment. For each domain, guiding design principles as also a selection of established process-intensified technologies are described. The selection is limited to technologies for which all necessary concept design information is available.