Education, industry, and the military rely on relevant and effective performance assessment to make key decisions. Qualification, promotion, advancement, hiring, firing, and training decisions are just some of the functions that rely on good performance assessment. This chapter explores issues, tools, and techniques for ensuring that performance assessment meets the goals of decision makers. Important considerations include the following: the task environment in which assessment takes place, the validity of the measures selected, the diversity and scope of the measures, and often the local political environment in which assessments are made. Unfortunately, primarily in education, assessment policy is a matter of intense political debate, and the debate is sustained by misinformation. For example, traditional paper and pencil assessment techniques have come under fire from those who do not feel they have the relevance they once did. Simulation-based training technologies in industry and the military have put more emphasis on performance assessment systems that show real-world work relevance. The chapter examines these topics.