Deficits in communicating one's wants and needs can have significant and detrimental effects on quality of life. Particularly for individuals with autism spectrum disorder (ASD) and other related disabilities, manding is a pivotal skill that influences long-term prognosis. Mand training is complex and relies on several components to facilitate acquisition. Various approaches have been developed to target this pivotal repertoire; however, it is unknown if there are common elements, or "critical components," among interventions. Identifying these components may support the design of mand training interventions for young children that are efficient and effective. In this systematic review, we synthesized the characteristics of 118 participants included in 45 single-case studies teaching preschool-aged children to mand. Findings indicated that most studies conduct preference assessments to inform target selection, manipulate motivating operations, and deliver specific reinforcement following the emission of the mand. This review reveals a gap in observing behavioral indication, teaching under both establishing operation (EO) and abolishing operation (AO) conditions, and failure to observe interactions with the consequent stimulus. Overall, the results suggest differences in the variables included in mand training interventions and those critical to acquisition of a functional mand repertoire cannot be determined. We discuss implications and directions for future research.