This Minisymposium aims to showcase recent advances in multiscale modeling techniques for the design and optimization of complex and engineered materials, with a focus on computational strategies that bridge microscale material features and macroscale structural performance. The session will gather contributions addressing the development, implementation, and application of numerical methods capable of capturing material behavior across multiple length scales—an essential capability for the accurate design of architected and heterogeneous materials such as metamaterials, functionally graded structures, and hierarchical composites. A central objective of the Minisymposium is to highlight how multiscale modeling can inform and enhance material and structural optimization processes. Contributions are expected to span a broad range of topics, including—but not limited to—homogenization techniques, computational micromechanics, topology optimization, hierarchical and concurrent multiscale frameworks, and the incorporation of fine-scale material descriptors into large-scale design workflows. Particular emphasis will be placed on models that support the design of materials with tailored mechanical, thermal, acoustic, or multifunctional properties, and that can be integrated into computational pipelines for structural optimization. The Minisymposium will also explore emerging paradigms in material design, such as the integration of data-driven approaches, reduced-order modeling, and machine learning techniques to accelerate multiscale simulations and inverse design processes. Contributions highlighting practical applications—ranging from additive manufacturing and energy systems to biomechanics and lightweight aerospace structures—are especially encouraged, particularly when they demonstrate the synergy between theoretical developments and real-world engineering challenges. In addition to presenting technical advances, the session will serve as a platform for discussing open challenges related to computational cost, model validation, uncertainty quantification, and the translation of optimized designs into manufacturable solutions. By fostering dialogue among experts in applied mathematics, solid mechanics, materials science, and computational engineering, the Minisymposium will offer a comprehensive overview of current efforts in multiscale modeling for material and structural design, while also helping to outline future research directions.