OBJECTIVES/GOALS: Frequent utilizers of emergency departments (ED) make up a substantial share of overall ED use. Within pediatric emergency departments (PED), infants represent an age group that make up a disproportionate share of PED visits. The objective was to compare patterns of PED use for children less than 1 year of age by visit frequency and resource utilization. METHODS/STUDY POPULATION: Retrospective cohort study of infants less than 1 year presenting to 5 EDs in one health system over a 5-year period, with a 365-day follow-up after each index visit. Patient characteristics (age, sex, race/ethnicity, presence of chronic condition) and visit characteristics (arrival day/time, acuity level, disposition, testing (labs and radiographs, medications) were assessed. The relationship between patient and visit characteristics with utilization and repeat visits was assessed using multivariable regression. RESULTS/ANTICIPATED RESULTS: A total of 20,620 patients with 33,127 ED visits during study timeframe. Thirty three percent (n=6842) had more than one visit in a year; 3964 (19.2%) had two visits, 1542 (7.5%) had three visits, and 1336 (6.5%) had 4 or more visits. Across all visits, over half (52%) were low acuity. The most common diagnoses were respiratory diseases (27%), systemic states (including fever, viral illness, 23%), and gastrointestinal diseases (15%). These diagnoses remained the most common for those with 1, 2, 3, and ≥ 4 ED visits during follow up. As ED visit frequency increased, there was an increase in percentage of children who were older, non-Hispanic Black, and triaged as low acuity. Infants with ≥ 4 ED visits were more likely to be without a chronic condition, have no medications or testing ordered, and be discharged. DISCUSSION/SIGNIFICANCE: There was high ED utilization for those without chronic conditions who were least likely to need medications, testing, and hospital admission. With increasing attention paid to high-utilization in healthcare, it is important to assess why infants use the ED at high rates and develop systems to improve high value care while decreasing resource burden.