Objective: Pain is an important component of health and function, and chronic pain can be a problem in its own right. The purpose of this report is to review the considerations surrounding pain measurement in the NIH Toolbox, as well as to describe the measurement tools that were adopted for inclusion in the NIH Toolbox assessment battery.Methods: Instruments to measure pain in the NIH Toolbox were selected on the basis of scholarly input from a diverse group of experts, as well as review of existing instruments, which include verbal rating scales, numerical rating scales, and graphical scales.Results: Brief self-report measures of pain intensity and pain interference were selected for inclusion in the core NIH Toolbox for use with adults. A 0 to 10 numerical rating scale was recommended for measuring pain intensity, and a 6-item Patient Reported Outcome Measurement Information System (PROMIS) short form for measuring pain interference. The 8-item PROMIS Pediatric Pain Interference measure was recommended as a supplemental measure. No specific measure was recommended for measuring pain intensity in children.Conclusions: Core and supplemental measures were recommended for the NIH Toolbox.Additional measures were reviewed for investigators who seek tools for measuring pain intensity in pediatric samples. Neurology Pain is an important component of health and function. The NIH Toolbox somatosensation team took responsibility for considering the best methods for evaluating pain in the general population. In the International Classification of Functioning, Disability and Health, sensory functions and pain are grouped together as body functions; however, sensation of pain is distinguished from sensory functions such as proprioception or touch, as well as functions related to temperature and other stimuli. 1 The definition of somatosensory function includes the "detection, discrimination, and recognition" of pain (Dunn et al., this issue). However, pain is more than a biological process and can be integral to function, role participation, and overall quality of life. As such, its assessment often becomes a primary end point in clinical trials and treatment effectiveness studies. This led the Toolbox team to consider pain and its assessment in parallel with somatosensory function and to dedicate separate manuscripts to discussions of pain and somatosensation.The science of pain measurement has benefited from recent advances in measurement approaches and applications.2-4 The field of outcomes research has well-developed, self-reported pain measures that have been validated in a range of acute and chronic medical conditions. For this reason, the team chose not to develop new pain measures but to adopt existing instruments that would add to the battery of tests included in the NIH Toolbox. In this article, we describe the importance of pain to the assessment of health and discuss its multidimensional nature. We