The Materials Research Science & Engineering Center (MRSEC) at the University of Pennsylvania pursues a multidisciplinary approach to solve fundamental materials problems that are likely to underlie future technologies, and thereby, substantially impact the research and educational needs of society. The Laboratory for Research on the Structure of Matter (LRSM) is the intellectual focal point of materials research at PENN. It hosts the MRSEC, which consists of four Interdisciplinary Research Groups (IRGs) plus continually evolving Seed projects. The MRSEC provides crucial support for faculty, postdoctoral fellows, and graduate students drawn from different disciplines, to tackle complex materials science projects that can only be addressed in a truly collaborative mode. In this way, the MRSEC exploits PENN's strength in the design, synthesis, characterization, theory and modeling to create and understand entirely new classes of materials. The broad expertise, sophisticated equipment, plus the technical and administrative infrastructure that exist in the LRSM enable these projects.