The paper explores some of the political assumptions implicit in the use of social cost‐benefit analysis, and the role of economic planners using this analysis. It is argued that the recent emphasis on income distribution in project planning techniques rests on questionable assumptions about the nature and intentions of governments. These techniques can be thought of as attempts to redistribute income ‘through the back door’. Some possible justification for the use of income distribution weights in project planning is given, but it is concluded that they are very much second best to direct macro‐economic policies and popular participation in planning.