M.A. / In accordance with literature indications that have established the need for psychotherapeutic outcome assessment instruments to determine the effects of psychotherapy, an exploratory and comparative study was conducted with anxiety disorder clients in private practice settings. The purpose of the study was to verify the recommendations made in the literature for the use of an idiographic method of outcome assessment (the Dyad Grid), as opposed to typically applied normative methods (the IPAT Anxiety Scale). The nature of the suggestions concerning the application of an idiographic method of outcome assessment, required the development of a theoretical framework which integrated the assessment procedure in an explanatory manner. To this end, the personal construct psychology view of anxiety was discussed in relation to repertory grid technique and prior outcome assessment research conducted with the Dyad Grid. On the basis of the personal construct approach to anxiety, a pre-test post-test research design was used to establish the utility of the Dyad Grid to discriminate between beneficial and nonbeneficial psychotherapy outcomes with anxiety disorder clients. The outcome results of the Dyad Grid assessments were compared with the results obtained from the IPAT Anxiety Scale, in conjunction with qualitative post-therapeutic ratings of benefit, or a lack of benefit, made by the client and therapist. The findings obtained on the basis of 14 case-studies are encouraging. The Dyad Grid displayed a statistically significant level of agreement with the client and therapist ratings of therapeutic outcome (onetailed, p = 0,05), whereas the IPAT Anxiety Scale did not. Though limited to a sample of convenience, and subject to an idiographic methodological bias, the discussion of the results indicated that the study provides support for the use of idiographic procedures as an alternative to nomothetic methods of outcome assessment. It is concluded that the initial success of the Dyad Grid in assessing psychotherapy outcome as beneficial or non-beneficial warrants further investigation with a large sample research design.