The Klausen Research Groups identifies innovative synthetic paradigms that control material structure from the atom to the bulk, enabling the emergence of new properties. This presentation will focus on macromolecular silanes, inclusive of clusters, polymers, and polymer networks. Silicon is the semiconductor behind technologies like computer chips, solar cells, and batteries. The conventional approach to silicon-based materials is “top-down”: in a high-temperature process sand (SiO2) is converted to silicon (Si) ingots, which is carved down to smaller components. This process only accesses the most thermodynamically stable form of silicon, leaving uncovered vast swaths of structure-function space. Can we instead build silicon from the bottom-up, atom-by-atom? Our approach realizes otherwise unknown structures and compositions. Inspired by the cyclic subunits embedded within crystalline silicon, we envisioned that cyclosilane “building blocks” functionalized at distinct sites with reactive groups (e.g., SiH2) could be elaborated via dehydrogenative coupling to the poly(cyclosilane)s, a new polymeric form of an essential semiconductor. We have realized unprecedented levels of stereochemical and architectural control of structure, from which structure-based control of light absorption has emerged. The presentation will conclude on a new direction for macromolecular silanes, focusing on the wide-ranging impact of silicon’s greater polarizability on polymer mechanical properties, from the single strand to the network.