High specific strength metals and alloys with face-centered cubic (FCC) and hexagonal close-packed (HCP) crystal structures are widely used in transport and aerospace applications due to their high strength-to-weight ratios and excellent high-temperature performance. However, their use is limited by low ductility and poor fracture toughness associated with anisotropy, limited slip activity, and twinning. Understanding void growth and failure mechanisms is therefore essential for improving their performance. Therefore, this thesis employs numerical analyses and micromechanical modeling to investigate the mechanisms that govern ductile failure and their influence on the macroscopic response of porous single and polycrystals with FCC and HCP lattice symmetries. The analyses incorporated the relevant deformation mechanisms at the local scale, and appropriate micro–macro transition schemes were used to link the microscopic behavior to the macroscopic response. A rate-dependent crystal plasticity model with slip and twinning was used to study void growth, coalescence, and collapse in porous FCC and HCP crystals through crystal plasticity finite element method (CPFEM) unit-cell simulations, accounting for anisotropy, stress state, and boundary conditions. The study further investigates the potential of describing the macroscopic response of porous crystals and polycrystals using micromechanical mean-field models. The proposed formulation employs an additive Mori–Tanaka scheme for porous single crystals and a three-scale model based on the additive self-consistent scheme for porous polycrystals. Both approaches are validated against full-field numerical analyses. In addition, a GTN-like yield criterion for porous crystals was developed, calibrated using unit-cell analyses, and it is well suited for the implementation into the finite element framework. The results show that the numerical and micromechanical approaches effectively capture the influence of microstructure and crystal lattice symmetry on void growth and the macroscopic response of metallic materials.