This paper uses about 26 million home sales to measure house price idiosyncratic risk for 7,580 U.S. zip codes during three periods: (1) when the U.S. housing market was stable (1996–2000), (2) booming (2001–2007) and (3) busting (2007–2012), and investigates the determinants of house price risk. We find very strong relationships between risk and some basic housing market characteristics. There is a U‐shaped relationship between risk and zip‐code level median household income; risk is higher in zip codes with more appreciation volatility; and risk is not compensated with higher appreciation.