Understanding change over time in one's ability to function as a professional is fundamental in the practice of clinical supervision. Drawing on developmental models of human behavior, a model of the development over time of therapy practice is presented. Specific domains of clinical practice and overriding structures that provide markers in assessing professional growth are defined and related to levels of therapist growth. The issue of continued supervision throughout professional life is addressed. The supervisory relationship is explored and related to therapist levels. A chapter called "Nuts and Bolts of Supervision" addresses a collection of issues basic to the supervisory process, including the importance of knowing the licensure and certification standards for a given field in mental health, the importance of documentation, the various foci of supervision, group supervision, differential supervision responsibilities, and aspects of the supervisory process. Additional chapters address "Supervision across Settings,""Supervisor Development and Training," and "Ethical and Legal Issues." Appendixes include: (1) "Case Presentation Format"; (2) "Supervisee Information Form"; (3) "Supervisee Levels Questionnaire - Revised"; (4) "Empirical Studies of Clinical Supervision." (EMK)