This chapter discusses several types of numerical models for metallurgical evolution. First, some basic notions of microstructure representations and microstructure state variables, some features of hardening and recovery and some features of recrystallization are recalled. Then, constitutive models coupled with state variables are introduced and examples of applications are given. Mean field methods are also presented and applied to necklace structures produced in discontinuous dynamic recrystallization. Finally, future trends are described, with an emphasis on digital material models and how they will provide powerful models of recrystallization on the microscopic scale. © 2012 Woodhead Publishing Limited. All rights reserved.