The abilities of 68 professional staff members (physicians, physician assistants, dietitians, nurses, and counselors) from 12 clinics of the Coronary Primary Prevention Trial of the Lipid Research Clinics Program in 28 specific skills fundamental to interviewing and counseling for medication adherence were examined. Each staff member was provided with confidential data regarding his or her abilities, and each clinic's trial director received the group data for his or her staff's possession and use of these skills. Analyses of trial-wide data showed substantial differences among clinics in possession and use of the skills, with overall greater strength in interviewing skills, as compared with assessment and counseling skills. No professional group consistently possessed most or fewest of these skills. It is suggested that trained non-physician personnel could be used to complement physician efforts to counsel patients for medication adherence.