Inclusion Criteria:  Age 18 months to 36 months at first research encounter  At least three separate wheezing episodes, as reported by parent/caregiver or patient's care provider and/or documented in the patient's medical record  Third episode may be at time of presentation to the emergency department (ED) or admission as inpatient (IP) to hospital when recruitment would occur (Visit ED/IP) Bronchiolitis and wheezing/asthma exacerbations are considered wheezing episodes The wheezing episode does not require treatment with bronchodilators  Live within a US Office of Management and Budget-defined Metropolitan Statistical Area (MSA) and meet at least one of these criteria:  Have publicly funded health insurance AND/OR Live in a census tract within an MSA where ≥10% of families have income below the poverty level  Exclusion Criteria:  Wheeze attributed to alternative diagnoses other than bronchiolitis or asthma, including congenital anatomical abnormalities, foreign body aspiration, chronic lung disease of prematurity, other chronic lung disorders such as cystic fibrosis, and cardiac, immune, and gastrointestinal disorders. Gestational age < 32 weeks.