Rapid development of training scenarios grounded in the principles of learning science has been an on-going challenge for the military. Typically, little, if any, attempt is made to utilize these principles in scenario development for several reasons. First, the literature in this area is highly varied in content, commonly focused upon K-12 education, and dispersed throughout education, psychology, and cognitive science journals. As a result, the ability of scenario developers to apply readily available scientific principles is significantly hindered. Second, due to the evolving battlespace, the immediate need for new or modified training products often outweighs the longer term advantage of a scientifically sound methodology for scenario creation. In response, this paper translates existing research from training science into actionable principles for scenario development. The recommendations are organized by trainee expertise level. Categories of recommendations include complexity level, length of scenario, feedback type and timing, knowledge acquisition goals, number of practice segments, and instructor type. Taken together, these principles will help developers tailor the format and content of training scenarios to address different types of learning, maximize knowledge acquisition, and adapt to levels of learning, while simultaneously decreasing the resources required to develop effective scenarios.