The habilitation thesis presents the crystal plasticity FEM (CPFEM) implementation and the included constitutive models that were developed in the research group of the author at the Max-Planck-Institut für Eisenforschung in the past 5 years. The implementation accounts for the versatility of CPFEM by including several constitutive models within one code. Therefore, it for the first time allows combining different constitutive models in a single FE model. The thesis is divided into three parts. After a general introduction to CPFEM the first part describes simulations at small scales also called direct CPFEM. For this purpose two non-local dislocation density based constitutive models are introduced in addition to the conventional empirical descriptions. The part is closed by a number of application examples demonstrating different aspects of direct CPFEM. The second part deals with component scale simulations. First models for texture discretization and homogenization are introduced. Second one more constitutive model implementing twinning as additional deformation mechanism is introduced. Finally, as in the first part, application examples demonstrate different aspects of component scale simulations. The third part finally introduces the implementation of the code and how it combines the different constitutive models.