Seasoned officers have important experiences to share with younger leaders. However, converting that knowledge into effective training can be challenging. Today's instructors and training developers are increasingly in search of easy-to-implement training solutions that can help them address and improve tactical assessment and decision-making skills. The use of scenario-based training methods is one solution. High-quality scenarios are built by subject-matter experts who have a thorough understanding of the domain and the kinds of decisions and assessments operators in those environments face. Narrated as if they are unfolding in real time, scenarios pose realistic situations that culminate in a dilemma which forces students to practice complex reasoning skills such as decision making, problem solving, and sensemaking. Scenario-based training also enables students to focus on specific learning objectives and provides reflective learning experiences to help build a student's experience base. Together, these elements form the "cognitive building blocks" for effective classroom training. This paper describes the research and development of a scenario-authoring assistant that helps instructors create scenarios for classroom and distance learning environments. The research objective was to succinctly define the best practices in scenario development from experts who create and employ scenarios on a regular basis. A component of the system under development will utilize a streamlined content development process that ensures that the training scenario will incorporate cognitive tasks, challenges, perceptual cues, environmental factors, and strategies that will develop junior leaders' assessment and decision skills. The system is intended to facilitate the development of a community of practice in scenario authoring. This will be accomplished by each user community continually contributing to a repository of scenarios, maps, graphics, icons, instructional tools, and lessons learned for future scenario developers to use.