abstract: Late preterm infants (LPIs), born between 34 and 37 weeks gestation, are at risk for a myriad of health conditions related to neuro-muscular and physiologic immaturity. However, relative stability allow many of these infants to avoid care in specialty nurseries and discharge home with their mothers after birth. Due to underlying immaturity, feeding difficulty is the most common issue LPIs experience, resulting in early breastfeeding cessation, increased risk for secondary diagnoses, and hospital readmission. The purpose of this study was to assess early breastfeeding behavior of LPIs, including testing inter-rater reliability of an assessment tool and the feeding patterns of infants over time. An extensive review of breastfeeding assessment tools resulted in the selection of the Premature Infant Breastfeeding Behavior Scale (PIBBS) based on its reliability and validity in the preterm infant population. A convenience sample of LPI dyads was recruited and used to conduct inter-rater reliability testing of PIBBS. A longitudinal one-group non-experimental study was used for observational follow-up. A strong statistical agreement of PIBBS scores occurred between mothers and a healthcare professional (Cohen’s kappa values of items ranged from .776 to 1.000, p = <.001). Participants continued using the PIBBS tool after hospital discharge until their infants expected due dates (40 weeks adjusted age). T-test analyses were conducted to examine changes in scores over time indicating increase in item scores (p = .003 - .193). PIBBS appears to be a valid and reliable tool to assess breastfeeding among LPI dyads. Incorporation of PIBBS into a comprehensive plan of care could better support and protect breastfeeding among the LPI population. / Dissertation/Thesis / Doctoral Dissertation Nursing and Healthcare Innovation 2018