This study provides evidence of the impact of an urban growth boundary (UGB) on housing and land prices. The study uses a data-set that inventories sales transactions of single-family homes and of vacant lots zoned for single-family homes within two miles of either side of the eastern boundary of the primary UGB in King County, Washington. The results show that although the UGB increases land prices by 230 per cent, it decreases housing prices by 1.3 per cent. These findings should encourage policy-makers to adopt a policy framework in which a UGB's anticipated inflationary land price effect is mitigated by policies that increase housing supply. Such policies could include minimum density requirements, zoning for multifamily housing, and ordinances enabling the construction of accessory dwelling units.