BACKGROUND: Preterm infants are especially vulnerable to infectious diseases. Although vaccinations are a safe and effective measure to protect preterm infants from vaccine-preventable diseases, delays in vaccinations are not uncommon. PURPOSE: The goal of this quality improvement project was to improve on time vaccinations of preterm infants hospitalized in the neonatal intensive care unit. METHODS: The Plan-Do-Study-Act model of quality improvement was adopted to develop, test, and implement interventions aimed at improving timely vaccination of preterm infants. The primary outcome measure of interest was the rate of on time vaccination, which was defined as the proportion of medically eligible preterm infants who received vaccinations within 2 weeks of the recommended schedule. RESULTS: Baseline on time vaccination rate was only 36%. Following several Plan-Do-Study-Act cycles, a steady increase in on time vaccinations of eligible infants was observed, and a new baseline on time vaccination rate of 82% was achieved. IMPLICATIONS FOR PRACTICE: Simple interventions implemented within the context of Plan-Do-Study-Act cycles are effective in improving timely vaccinations among preterm infants. IMPLICATIONS FOR RESEARCH: Future research that focuses on vaccinations in preterm infants is needed to further reinforce the safety and efficacy of vaccines. Effective methods on how to disseminate and apply this knowledge to practice should also be studied.Video Abstract available at http://links.lww.com/ANC/A27.