Classical crystal plasticity (CP) theory accounts for the crystalline microstructure, i.e. the slip systems of an underlying crystalline lattice. Regarding polycrystals, the overall mechanical behavior is significantly affected by grain boundariers (GBs), which are modeled as material singular surfaces in classical continuum mechanics, cf., e.g., [1]. In the context of microstructure evolution, the tracking of these sharp interface (SI) GBs is challenging and numerically costly. This can be circumvented by the implementation of the CP in the framework of the multiphase-field method (MPFM), representing an efficient method for the treatment of moving surfaces, modeling them as diffuse interfaces of finite thickness. Within the diffuse interface region, the material behavior is implemented by means of the jump condition approach, cf., e.g., [2]. Three dimensional simulations of a bicrystal illustrate the consistency between the MPFM-solution and the SI-solution. In addition, the growth of an elastic inclusion in an elastoplastic matrix under load, exhibiting CP behavior, is discussed. Further investigations of the evolution of a polycrstalline microstructure after an elastoplastic deformation are presented, representing preliminary work of mimicking recrystallization processes. REFERENCES [1] A. Prahs, T. Böhlke, On interface conditions on a material singular surface, Contin. Mech. Thermodyn, Vol. 32, 1417–1434, 2019. [2] D. Schneider, F. Schwab. E. Schoof, A. Reiter, C. Herrmann, M. Selzer, T. Böhlke, B. Nestler, On the stress calculation within phase-field approaches: a model for finite deformations, Comput. Mech., Vol. 60 (2), 203–217, 2017.