The purpose of this article is to discuss the validit l and reliabilit y of 'certification tests and evaluation instruments for pharmacists as drug prescribers. Under California Law AB 717, the University of'Southern California is operating one of two pilot programs to train and evaluate prescribing iharmacists. Various instruments have heen created and administered, and validity results are presented. The presentation is organized into two areas dealing with the development of' the examination instrumient and then the assessment of'the prescriptions written by pharmacists. The reliability of' the three sections of the certification examination as mneasured hi internal consistencyl was as fbllows: clinical therapeutics (KR 20=.84), physical assessment (KR 20 =.88), and law (KR 20= .84). The exam was given to a group of physicians (N = 14) to establish a cutting score. Thirty pharmacists who took the exam didslightlY better than the phi sicians on clinical therapeutics, but the ph} vsicians perfornied better than pharmacists on physical assessment (p <.01). A prescription evaluation form was (constructed to evaluate the performance of the pharmacists as prescribers. The reliability of the form as measured b y (coej, ficient alpha was .84. Concurrent validit Y was explored bY assessing the relationship between perfbrmance on the certification exam and judges' appropriateness scores on prescriptions for ambulator he pertensive patients. These results indicate that the pharmacists, who passed the exam, can prescribe as appropriatelY as physicians.