This chapter examines the maintenance environment and maintenance tasks to explain how antecedents to error in maintenance tasks can occur. If hands-free operation is not possible, the technician's ability to work effectively will be impeded, either because of constraints from the use of only one hand, or because of the poor illumination, leading to a maintenance or inspection error. The research community has only focused on the maintenance environment and distinctive features of inspection and maintenance that can become antecedents to error. Most errors take place in performing the maintenance task itself, largely because of difficulties in the maintenance environment, the task itself, or the tools and parts used. Maintenance personnel work directly on system equipment, and equipment location and design features dictate many of the parameters of their work environment. Evaluation and inspection are subject to distinctive antecedents and, depending on the procedures, the setting, and the type of task performed, the rate of detecting flaws may vary.