This chapter provides a systematic approach to determining user needs, developing usability objectives, analyzing and modifying existing tasks, and designing new tasks. Task analysis is the analysis of work activities and breaking them down to an appropriate level of detail to enable the determination of behaviors, skills and knowledge. Deficiencies of execution, however, are a function of task interference, lack of feedback, or insufficient consequences to the performer. Data concerning the target population, task characteristics and the environment can be obtained from a number of different sources. A responsibility can be defined as a portion of a job that includes two or more related tasks and is performed to meet a specific goal. If task information must be extracted from existing documentation, the analyst will need to extract the tasks from that documentation. The design of new tasks is much harder than the analysis and description of existing performance and requires considerable knowledge of human behavior.