High-risk neonates experience numerous painful/stressful procedures daily in neonatal intensive care units (NICUs). Accumulated pain and stress have a detrimental impact on infants' neurodevelopment. Few valid tools are available to measure accumulated pain/stressors among NICU infants. The aim of this study was to obtain nurses' perceptions about severity and acuity levels regarding each painful/stressful procedure that infants may experience in the NICU. The data will support developing a new instrument, the Accumulated Pain/Stressor Scale (APSS) in NICUs. A nationwide online survey was conducted through the U.S. National Association of Neonatal Nurses membership. Respondents were asked to rate the perceived severity of pain/stress associated with 68 procedures using a 5-point Likert scale and to categorize pain/stress as acute or chronic. Modal values were used to determine summary rankings among the procedures. Eighty-four neonatal nurses completed the survey. Among 68 procedures, nearly all were rated as painful/stressful to some degree. Five procedures (7%) had a modal value of five (extremely painful/stressful), nine (14%) had a value of four, 20 (29%) had a value of three, 30 (44%) a value of two, and four (6%) had a value of one (not painful/stressful). Forty-four procedures (65%) were perceived as acute, six (9%) as chronic, and 18 (26%) as both acute and chronic. Nurses' perceptions of pain severity and acuity regarding procedures in NICUs varied somewhat. Further studies are needed in developing and validating the scale. The development of the APSS can quantitatively measure the accumulated neonatal pain/stress.