The present paper is the first in a series reporting on the development of a pre-employment selection program for psychiatric aides at the VA Hospital, Coatsville, Pennsylvania.1. A survey of previous research in the area of aide selection suggests that equivocal, ambiguous, and only partly useful results have been obtained because of the lack of an adequate criterion of effectiveness of job performance.2. Flanagan's Critical Incident Technique was used to develop a list of critical requirements for the job of psychiatric aide. Critical incidents were collected in prepared booklets from the professional staff of the hospital, supervisory and floor nurses, student nurses, and other personnel who routinely come into contact with aides in the course of their work.3. An attempt to use booklets for the collection of critical incidents from aides was unsuccessful. Satisfactory response was obtained by interviewing the aides individually.4. A total of 1,123 incidents was obtained from 325 respondents. These were sorted and categorized into 7 major areas and 22 subareas of job requirements.5. Suggestions are made as to how these findings may be applied in other hospitals. Later papers will report on their specific application in this hospital.Abstract Teaser