Behavioral observation systems allow for a relatively objective way to record important academic, behavioral, and/or interactional processes. Not surprisingly, the majority of school-based observational methods have been designed for and evaluated within the classroom setting. Although this is understandable, the playground context during recess provides an important unstructured school context in which to understand young children's peer relationships, play behaviors, and aggressive actions. This article provides a critical review of six playground-based observation systems and discusses implications for use by practitioners and researchers. (Contains 1 table.)