Assessment in clinical practice is a complex role undertaken by mentors and practice teachers. Therefore, this and the following two articles in this series will explore student assessment in clinical practice and the theoretical concepts that relate to assessment of learning and development. This article examines the importance of assessment and the role of mentors and practice teachers in this activity. Definitions and the purpose of assessment are analysed, in addition to various assessment methods used in clinical practice that relate to the third domain and outcomes of the Nursing and Midwifery Council’s Standards to Support Learning and Assessment in Practice on assessment and accountability.