Pain assessment documentation was inadequate because of the use of a subjective pain assessment strategy in a tertiary level IV neonatal intensive care unit (NICU). The aim of this study was to improve consistency of pain assessment documentation through implementation of a multidimensional neonatal pain and sedation assessment tool. The study was set in a 60-bed level IV NICU within an urban children's hospital. Participants included NICU staff, including registered nurses, neonatal nurse practitioners, clinical nurse specialists, pharmacists, neonatal fellows, and neonatologists. The Plan Do Study Act method of quality improvement was used for this project. Baseline assessment included review of patient medical records 6 months before the intervention. Documentation of pain assessment on admission, routine pain assessment, reassessment of pain after an elevated pain score, discussion of pain in multidisciplinary rounds, and documentation of pain assessment were reviewed. Literature review and listserv query were conducted to identify neonatal pain tools. Survey of staff was conducted to evaluate knowledge of neonatal pain and also to determine current healthcare providers' practice as related to identification and treatment of neonatal pain. A multidimensional neonatal pain tool, the Neonatal Pain, Agitation, and Sedation Scale (N-PASS), was chosen by the staff for implementation. Six months and 2 years following education on the use of the N-PASS and implementation in the NICU, a chart review of all hospitalized patients was conducted to evaluate documentation of pain assessment on admission, routine pain assessment, reassessment of pain after an elevated pain score, discussion of pain in multidisciplinary rounds, and documentation of pain assessment in the medical progress note. Documentation of pain scores improved from 60% to 100% at 6 months and remained at 99% 2 years following implementation of the N-PASS. Pain score documentation with ongoing nursing assessment improved from 55% to greater than 90% at 6 months and 2 years following the intervention. Pain assessment documentation following intervention of an elevated pain score was 0% before implementation of the N-PASS and improved slightly to 30% 6 months and 47% 2 years following implementation. Identification and implementation of a multidimensional neonatal pain assessment tool, the N-PASS, improved documentation of pain in our unit. Although improvement in all quality improvement monitors was noted, additional work is needed in several key areas, specifically documentation of reassessment of pain following an intervention for an elevated pain score.