Procedures can greatly benefit workers at tasks such as inspection, maintenance, and assembly. Procedures may serve as a guideline for expert workers or they may provide a list of directives to be followed exactly; either way, procedures serve to structure a task, to aid worker memory, and to guarantee consistency and safety. Light, inexpensive electronics may allow for the development of task guidance systems to further help workers by presenting procedures and associated information about the task. This article reviews the current state of knowledge about the development of task guidance systems, and highlights their potential value in a variety of domains. First, the characteristics of procedural tasks are discussed, as a basis for a discussion on the benefits of procedure following that task guidance systems can support, and potential problems in procedure following that task guidance systems can mitigate. Then, current research results in task guidance systems are summarized. Finally, a discussion is given on the contextual information that a task guidance system may need to provide.