This textbook on assessment is written for both occupational therapy and physiotherapy students. It begins by defining what is meant by assessment and discussing its complexity, including the challenge of measuring human behaviour and the impact of the environment. Methods and sources for collecting information about clients are then reviewed, and the main purposes of assessment presented. The book then addresses the topics of standardisation and levels of measurement and describes models for categorizing levels of function. The concept of clinical reasoning is then explored and illustrated with case studies, and the criteria for choosing a particular assessment approach are discussed. Introduction 1: The importance of accurate assessment and outcome measurement  2: Methods of assessment and sources of assessment data 3: Purposes of assessment and measurement 4: Levels of measurement 5: Standardisation and test development 6: Validity and clinical utility 7: Reliability 8: Test administration, reporting and recording 9: Applying models of function to therapy assessment and measurement 10: The importance of clinical reasoning and reflective practice in effective assessment 11: Implementing the optimum assessment and measurement approach 12: The Final Case Study: Carol experience of a Chronic Pain Service