Learning objects (LOs) are essential building blocks of Sharable Content Object Reference Model (SCORM)-conformant training and performance support systems, and have been the subject of extensive research, development, and application efforts. A close relative to the LO is the knowledge object (KO) which is undergoing a semantic and structural identity crisis. Some practitioners consider KOs equivalent to LOs; others see KOs as structural components of LOs; still others see KOs and LOs to be ill-defined, unrelated entities. In short, there has been a diversity of opinion about the defining characteristics of KOs, their essential components and structure, and their relationship to LOs. Merrill and his colleagues provided insights on KOs during the exposition of his Instructional Transaction Theory in the 1990s. There has been a recent increase in interest in KOs, evidenced by theoretical and application issues addressed in the International Journal of Knowledge Objects and Learning Objects and related publications, as well as in less formal treatises on the Internet. The premise of this paper is that there is a need for a better understanding of, and utilization guidelines for, KOs used in training and performance support. Specifically, there is a need to address key KO issues such as how to: 1) achieve free-standing KOs, 2) make KOs usable across multiple contexts; 3) define an appropriate tagging standard, 4) standardize KO terminology, presentation tone, and keywords, and 5) facilitate the contextualization of content. In this paper we provide a critical review of KOs and LOs, address KO issues, and make practical recommendations for their effective use. To provide real-world context, we briefly reference ongoing work by the U.S. Defense Ammunition Center to develop and implement KOs in the operational domains of ammunition safety hazardous materials transportation.