The paper describes the psychometric properties of the PROMIS Pain Interference (PROMIS-PI) item bank. An initial candidate item pool of 644 items was developed and evaluated based on existing instruments, patient interviews, and expert consultation. From this pool, 56 items were selected and responses were collected from large community and clinical samples, resulting in 14,848 participants responding to the items. Responses were calibrated using an item response theory (IRT) model. A final 41-item bank was evaluated for IRT assumptions, model fit, differential item function (DIF), precision, and construct validity. The items showed good fit to the IRT model (CFI and NNFI/TLI ranged from 0.974 to 0.997), and the data were strongly unidimensional. Nine items exhibited statistically significant DIF, but adjusting for DIF had little practical impact on score estimates. Scores provided substantial information across levels of pain, with reliability equivalent to 0.96 to 0.99 for scores in the T-score range 50-80. Patterns of correlations with other health outcomes supported construct validity. The scores discriminated among persons with different numbers of chronic conditions, disabling conditions, levels of self-reported health, and pain intensity. The results indicated that the PROMIS-PI items constitute a psychometrically sound bank. Computerized adaptive testing and short forms are available. The PROMIS-PI item bank was developed to measure pain interference, with the aim of providing reliable scores with minimal respondent burden and minimal DIF. The item bank was validated using data from community and clinical samples, and the results supported the construct validity of the item bank. The item bank was also evaluated for DIF, with nine items showing statistically significant DIF. However, adjusting for DIF had little practical impact on score estimates. The item bank was found to be reliable and valid for measuring pain interference. The results suggest that the PROMIS-PI item bank is a psychometrically sound tool for assessing the negative effects of pain on functioning.The paper describes the psychometric properties of the PROMIS Pain Interference (PROMIS-PI) item bank. An initial candidate item pool of 644 items was developed and evaluated based on existing instruments, patient interviews, and expert consultation. From this pool, 56 items were selected and responses were collected from large community and clinical samples, resulting in 14,848 participants responding to the items. Responses were calibrated using an item response theory (IRT) model. A final 41-item bank was evaluated for IRT assumptions, model fit, differential item function (DIF), precision, and construct validity. The items showed good fit to the IRT model (CFI and NNFI/TLI ranged from 0.974 to 0.997), and the data were strongly unidimensional. Nine items exhibited statistically significant DIF, but adjusting for DIF had little practical impact on score estimates. Scores provided substantial information across levels of pain, with reliability equivalent to 0.96 to 0.99 for scores in the T-score range 50-80. Patterns of correlations with other health outcomes supported construct validity. The scores discriminated among persons with different numbers of chronic conditions, disabling conditions, levels of self-reported health, and pain intensity. The results indicated that the PROMIS-PI items constitute a psychometrically sound bank. Computerized adaptive testing and short forms are available. The PROMIS-PI item bank was developed to measure pain interference, with the aim of providing reliable scores with minimal respondent burden and minimal DIF. The item bank was validated using data from community and clinical samples, and the results supported the construct validity of the item bank. The item bank was also evaluated for DIF, with nine items showing statistically significant DIF. However, adjusting for DIF had little practical impact on score estimates. The item bank was found to be reliable and valid for measuring pain interference. The results suggest that the PROMIS-PI item bank is a psychometrically sound tool for assessing the negative effects of pain on functioning.