This chapter identifies the critical scales for achieving successful multiscale modeling and simulations of metallic materials in plasticity. To that end, we will look into the hierarchical structure based on the viewpoints provided in Part I. The breaking down of the hierarchical scales in plasticity into finite numbers of representative scales of critical importance, in combination with the extensive use of the FTMP-based models, is expected to convert many of practically-important- but-difficult-to-solve problems much easier for us to tackle. As such examples, three research projects in progress of the author’s own are outlined next. The contents provided there will effectively lead us to step forward to the following three chapters in Part III, where FTMP-based approaches, models and perspectives are applied to the identified individual scales.