Passing scores for licensure and certification tests are justified by showing that decisions based on the passing score achieve the purposes of the credentialing program while avoiding any serious negative consequences. The standard should be high enough to provide adequate protection for the public, and not so high as to unnecessarily restrict the supply of qualified practitioners or to exclude competent candidates from practicing. This paper begins by examining the intended outcomes of licensure and certification programs and by outlining the interpretive argument that is typically used for written credentialing examinations. Criteria are then developed for evaluating standard-setting methods in terms of how well they serve the goals of protecting the public, maintaining an adequate supply of practitioners, and protecting the rights of candidates. Finally, the criteria are used to evaluate the Angoff method. This analysis identifies two potential sources of bias in the Angoff method, and suggests ways to control these weaknesses.