Documenting the level of ethnic residential and school segregation in Copenhagen shows low levels of residential segregation due to suburbanisation (opposite to the US experience), but high levels of school segregation, which for some student groups reach levels comparable to the extreme segregation typical for US cities. Thus, the evidence from Copenhagen suggests that low residential segregation does not necessarily translate into moderate school segregation: when school choice options are available (public and, in particular, private), low residential segregation is compatible with high school segregation levels. A decomposition suggests that socioeconomic differences do not seem to be the main driving-force behind school segregation.