ABSTRACTDiscussion of the problems involved in assessing the effects of therapies offered to aphasic patients appears to have become a dispute about methodology. Since it is important that therapists devote more effort to experimentally evaluating therapy, uncertainty about the appropriate methodology is unlikely to be helpful. The choice of methodology in this instance reflects the current state of knowledge about aphasia therapy and the nature of the questions we wish to answer. Since therapists will wish to discover effective therapies further large scale studies of the general impact of therapy are unlikely to be informative.