For a century, zoning—the local-government regulation of land use, structures, and lots through the assignment of lots to distinctly regulated districts—has dictated how and where we live. As zoning enters its second century, there is a strong drumbeat for reform. Reformers have most explicitly targeted the elimination of single-family zoning, pointing to research showing that single-family zoning drives up development costs, degrades the environment, and makes communities too homogenous. While these negative effects are real, simply lifting bans on multi-family housing may not actually create more housing options, because zoning is far more complex than the number-of-units measure alone. Process requirements like mandatory public hearings and substantive requirements involving lot configuration, building size, and occupancy, among other things, play a significant role in determining whether and what residential development occurs. Understanding how all of these aspects of zoning codes affect the supply of housing is needed to truly understand what to advocate for. Yet high-quality, reliable data that could drive activism in general, and the most impactful types of reform more specifically, is missing. This Article’s central claim is that our simplistic approach to zoning reform results in part from the lack of sophisticated empirical data documenting about the many hidden constraints on housing embedded in zoning codes across jurisdictions. The Article exposes how both legal scholars and economists have drawn conclusions from unreliable or incomplete data. As a result, current zoning research cannot be relied upon to inform broad policy choices at any scale. Using a dataset that overcomes the reliability and comprehensiveness flaws of prior research, this Article shows how zoning kills housing by a thousand cuts in Connecticut. Mining this dataset, then replicating it elsewhere, will help us more definitively illuminate the effects of zoning nationally. This Article closes by reinforcing calls for a national dataset tracking how zoning codes treat housing, using the Connecticut methods and data collected as a starting point. Ultimately, this Article seeks to expose the hidden levers of zoning and to encourage both scholars and reformers to document and quantify the requirements that incrementally strangle the national supply of housing.