Applied Optics The realization of optical frequency combs, light sources with precisely spaced frequencies across a broad spectrum of wavelengths, in dielectric microresonators has affected a range of applications from imaging and ranging to precision time keeping and metrology. Xiang et al. demonstrate that the entire system, the laser-pumping system and the comb-generating microresonators, can be combined into an integrated silicon-based platform. Compatibility with foundry fabrication methods will enable this innovation to have a major impact on coherent communications, optical interconnects, and low-noise microwave generation. Science , abh2076, this issue p. [99][1] [1]: /lookup/doi/10.1126/science.abh2076