The distinctive features of well‐defined, three‐dimensional macromolecules with topologies designed to enhance solubility and amplify end‐group functionality facilitated nanophase morphologies in mixtures with organosilicates and ultimately nanoporous organosilicate networks. Novel macromolecular architectures including dendritic and star‐shaped polymers and organic nanoparticles were prepared by a modular approach from several libraries of building blocks including various generations of dendritic initiators and dendrons, selectively placed to amplify functionality and/or arm number, coupled with living polymerization techniques. Mixtures of an organosilicate and the macromolecular template were deposited, cured, and the phase separation of the organic component, organized the vitrifying organosilicate into nanostructures. Removal of the sacrificial macromolecular template, also denoted as porogen, by thermolysis, yielded the desired nanoporous organosilicate, and the size scale of phase separation was strongly dependent on the chain topology. These materials were designed for use as interlayer, ultra‐low dielectric insulators for on‐chip applications with dielectric constant values as low as 1.5. The porogen design, chemistry and role of polymer architecture on hybrid and pore morphology will be emphasized. Novel macromolecular architectures including dendritic and star‐shaped polymers and organic nanoparticles are synthesized based on a modular approach from several libraries of building blocks including functional dendrimers (see picture) and dendrons. One of the distinctive features of these well‐defined three‐dimensional macromolecules is to facilitate nanophase morphologies in mixtures with organosilicates and ultimately, upon thermolysis of the organic component, nanoporous organosilicate networks.