Presented are four instruments current in rehabilitation diagnostics. They are investigated concerning their usefulness and merit as well as their possibly specific approach, starting out from the World Health Organization's International Classification of Impairments, Disabilities, and Handicaps (ICIDH), which so far has hardly been commented on in the German-language area, with its effort of enabling severity-specific assessment of need and its extensive exposition on the part of the editor of "problem awareness" in relation to the subsequent planes of consideration. The EAM system is focussed on occupationally integrative, job-specific appraisal, attempting to implement standardized performance/adaptation analysis. This is contrasted with the subjective criteria-based, very consistent IRES questionnaire, which however lacks objective severity appraisal. Additionally dealt with is the "RPK" procedure used in evaluating the rehabilitation of persons with chronic mental illness. Overall, it is found that each of the different instruments has its value and merits, although major aspects of rehabilitation and, above all, integration prognosis require differentiated, systemic appraisal and on-going rehabilitation-specific consideration. What is needed is "understanding" the nature of disease consequences at the different planes of experience.