The chapter highlights formative, summative, and high-stakes assessments in simulation, emphasizing their roles in enhancing clinical competence. Assessment tools like checklists, rating scales, and rubrics are detailed, with characteristics for each. The importance of validity and reliability in simulation assessment is discussed, with insights into construct, content, and criterion validity, along with test-retest, interrater, and internal consistency reliability. Practical tips for ensuring validity and reliability are provided. The chapter concludes by underscoring the pivotal role of effective assessment in maximizing educational benefits in healthcare simulation.