Most people come to evaluation with an ulterior motive - whether they recognise it or not. They are looking for a reason, for an excuse or perhaps a justification. For some, evaluation is an instrument of power. Without having to reach the highest administrative levels, they find themselves allowed to pronounce on the projects and programmes of so many others : and there is something enticingly God-like about making judgements without actually carrying responsibility. That is why evaluators should not themselves be immune from evaluation. There are those seeking to establish the efficiency of the services in which they work or for which they carry responsibility. They may try genuinely to be detached and objective but we cannot be surprised if they lean towards the evaluative methods which justify their policies and reinforce their own preconceptions. Then there are the technically minded, the methodologically committed, the honest devotees of cost-benefit analysis. They really believe that the medium is the message, that the process is what matters and that values that cannot be quantified just get in the way.