The Patient-Reported Outcomes Measurement Information System (PROMIS) is an NIH Roadmap initiative to develop a computerized system measuring patient-reported outcomes in respondents with a wide range of chronic diseases and demographic characteristics. In the first four years of its existence, the PROMIS network developed item banks for measuring patient-reported outcomes in the areas of pain, fatigue, emotional distress, physical function, and social functioning. During the item banking process, the PROMIS network conducted focus groups, individual cognitive interviews, and lexile (reading level) analyses to refine the meaning, clarity, and literacy demands of all items. The item banks were administered to over 20,000 respondents and calibrated using models based on item response theory (IRT). Using these IRT calibrations, computerized adaptive test (CAT) algorithms were developed and implemented. The network has designed a series of studies using clinical populations to evaluate the item attributes, examine their utility as CATs, and validate the item banks. More information on the PROMIS network can be found at www.nihpromis.org.