1. Are male or female aged 6-17 years, inclusive, at Screening and Enrollment Visit (Visit 0). 2. Have a primary place of residence in one of the pre-selected recruitment census tracts as outlined in the ICAC MOP. 3. Have a diagnosis of asthma made by a clinician >1 year prior to recruitment. 4. Have had at least 2 asthma exacerbations in the prior year, defined as a requirement for systemic corticosteroids and/or hospitalization. 5. Have the following requirement for asthma controller medication at the Screening and Enrollment Visit (Visit 0) according to the MEDS program[4, 28]: i. For participants aged 6 to 11 years, treatment with at least fluticasone 250 mcg 1 puff twice daily or its equivalent. ii. For participants aged 12 years and older, treatment with at least Advair 250/50 mcg 1 puff twice daily or its equivalent. 6. Have peripheral blood eosinophils >=150 per mm3. Results can be obtained from participation in a previous ICAC study if obtained within 6 months of the Screening and Enrollment Visit (Visit 0). 7. Are currently a non-smoker. 8. Parent/legal guardian is willing to sign the written informed consent. 9. Are willing to sign the assent form as per central IRB guidelines. 10. Have some form of insurance that covers costs of usual care asthma control and rescue medications at the Screening and Enrollment Visit (Visit 0).