Second only to the common cold, pain is the most common reason for health care visits. It results in significant personal and social costs to individuals, and economic costs to society. Chronic pain has been estimated to cost more than 100 billion annually in the United States, and its estimated annual cost to European countries ranges from 1.1 to nearly 50 billion Euros (nearly 1.5 billion to over 60 billion dollars). In order to treat pain, clinicians need to be able to assess pain and its effects on functioning. However, 100s, if not 1000s, of different measures of pain and pain-related domains exist. Surprisingly, despite the fact that much is known about the psychometrics strengths and weaknesses of existing measures, there does not yet exist a simple pain assessment guide that describes the most useful and psychometrically sound pain measures for health care providers. This book fills this need.