A preceptorship model of clinical teaching for medical education is presented. Based on the view that physicians use precepting skills in patient care, preceptorship is seen as an opportunity for medical students to learn to practice ambulatory medicine away from the medical center. A model called "Johari Window" is adapted to explain the preceptor's role, and specifically the kinds of information people bring to every action: knowledge, attitudes, and skills. The model clarifies the two functions of clinical teaching: assessment and instruction. Assessment involves questioning, professional intimacy, and observation, while instruction involves shared experience, role modeling, and demonstration and practice. The model also includes feedback and evaluation. Five levels of questioning can be used to assess a learner's knowledge. Assessing professional attitudes and behaviors is analogous to assessing patient health care beliefs. Ways to encourage the preceptee (and patient) include developing rapport and genuine interest, and being accessible, empathetic, and nonjudgmental. The techniques of brainstorming, questioning, challenging, and summarizing are helpful in making the student a more active learner. Additional techniques for instruction, demonstration and practice, and feedback and evaluation are suggested. (SW)