This study investigates the level of knowledge of clinical supervision among rehabilitation supervisors who provide clinical, administrative, and both clinical and administrative supervision. Moreover, the study intends to identify the knowledge domains that are important to providing clinical supervision in rehabilitation. In examining the knowledge domains for clinical supervision in rehabilitation The Rehabilitation Counselor Supervision Inventory (RCSI) was utilized. More than 120 rehabilitation supervisors employed within state-federal vocational rehabilitation field offices, community rehabilitation programs, and centers for independent living in Illinois comprised the sample. Participants completed the knowledge and skills domain portion of the RCSI. Descriptive statistics were computed on the six clinical supervision knowledge domains on the RCSI in order to examine the mean and standard deviation for the subjects' responses to the knowledge and skills scale. For the study, the supervisors rated the following clinical supervision knowledge and skills domains in order of importance: ethical and legal issues, rehabilitation counseling knowledge, intervention techniques and models, assessment and evaluation, supervisory relationship, and theories and models. Multiple linear regression analyses were utilized to assess the relationship between perceived importance of the clinical supervision knowledge domains on supervisory role (clinical, administrative, and both clinical and administrative supervisory roles). Results of multiple regression analyses indicated that supervisory role statistically predicted supervisors' perceptions of importance on four of the six clinical supervision knowledge domains on the RCSI. Understanding the relative importance of clinical supervision knowledge domains in the area of rehabilitation counseling will add to the existing body of research and literature specific to rehabilitation supervision and may assist in the development of appropriate training for supervisors who provide both clinical and administrative supervision. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]