When the National Institutes of Health was designing two new cleanroom research facilities, it faced familiar development challenges, including space constraints on an already-crowded campus, strict cleanroom guidelines, and the urgency to get scientists in the lab. The solution: prefabricated modular units. Executed well, the modular units shorten the design and construction schedule, provide better-quality spaces than stick-built laboratories or those employing modular panels that require on-site construction, and perform better for the scientific researchers who work in them.