This chapter considers assessment within a competency-based education (CBE) system. It addresses the practical problem of reliability and ways to improve it. The chapter introduces key dimensions of competency-based assessment to guide the design and conduct of assessment. It considers kinds of evidence appropriate to competency-based assessment, including evidence relating to performance and evidence relating to knowledge and understanding. The chapter examines the relationship between evaluation and assessment before looking at the differences between criterion-referenced and norm-referenced kinds of assessment. The principles of criterion-referenced assessment were developed independently of CBE, and from the start this kind of assessment was amenable to grading. Assessment against criteria demands some kind of evidence that the assessee can perform or has knowledge as specified. Assessment is usually thought of as something that happens after training—taking a measure of the learning that the assessee can demonstrate. CBE presents a range of challenges and opportunities for improving assessment in the industry.