When results of potency testing of a compounded preparation do not meet the desired specifications, concerns abound and questions are presented. The purpose of this article is to address some of the most common questions and to provide potential solutions. It addresses the investigative process used to determine the cause of unexpected potency test results, defines the term "out-of-specification," discusses the organization responsible for defining the acceptable specifications, explains the differences between a laboratory out-of-specification and a compounded preparation out-of-specification, describes the retesting procedure, outlines some of the possible reasons and remedies for out-of-specification results, and suggests practices to minimize error in compounding preparations. Compounding pharmacists should consider making the references and resource provided in this article readily available at their compounding facility.