The European Commission in Brussels ran a Poverty Programme of action projects and cross-national studies from 1975–80. An evaluation agency was set up by the Commission and carried out an evaluation of the Programme during 1979–80. This paper draws upon the experiences of that exercise in order to examine the concept and the practical implementation of a cross-national evaluation. It explores the political context of evaluation and the dilemmas and obstacles this poses for the evaluator. An evaluation exercise is an intrusion into the existing pattern of relationships among the various participants in the programme concerned. They will typically see it as an attempt at improved scrutiny and political control by its instigators – and the evaluator will therefore face a diplomatic as well as a technical task, particular vis-à-vis those participants upon whom he is dependent for the preparation of his report. This diplomacy will not take place in a vacuum, however, and its course will depend crucially upon the wider political context within which the future of the programme is being decided.