Project Summary Wheezing during preschool years is a common occurrence [1] causing significant healthcare burden [2] with frequent unscheduled physician visits, ED visits, hospitalizations, and treatment with inhaled and systemic corticosteroids along with other medications. Recurrent wheezing is often the antecedent to asthma, one of the most common chronic diseases of childhood. Though there is evidence of significant neurocognitive problems in children with other chronic health conditions such as oncological diseases, diabetes, heart disease, sickle cell, and traumatic brain injury [3], the impact of recurrent wheezing illnesses and associated treatment on the neurocognitive and emotional development of infants and preschool children has not been fully characterized. The ECHO cohort study has been collecting neurodevelopmental measures in children after the late preschool years; however, critical neurodevelopmental trajectories occur in early infancy [4]. Data suggest that these trajectories can be affected by pre-natal conditions, socioeconomic status, stress, disease severity, and/or medication use. A recent study, in non-asthmatic patients, showed that the use of systemic corticosteroids, a frequently administered treatment for wheezing illnesses, was associated with changes in brain structure [5]. Building on these findings, our overarching study objective is to understand the association of recurrent wheezing illnesses and its associated treatment on the neurocognitive and emotional development of infants and preschool children.