In their new business plan the operators of Schiphol Airport have announced their intention to increase the number of main runways from five in 2003 to six and possibly seven by 2020. At the request of the Amsterdam city environment department, CE examined whether the municipality of Amsterdam also stands to gain from expansion. The National Office for Economic Policy Analysis (CPB) recently completed an analysis of the chief social impacts of airport expansion at the national level. One of the main conclusions of that report was that the external costs of noise nuisance and other impacts are more than offset by user benefits. This conclusion appears to hold specifically for Amsterdam, too. The main area of uncertainty concerns the (shape and size of) noise contours post-expansion, and in particular their bearing on exclusion zones for residential and commercial development. According to our analysis, CPB underestimates both the noise-affected area and the costs of non-development per square metre. On this point, then, airport expansion will give Amsterdam municipal planners more problems and therefore expenditure than calculated by CPB.