For Aims 2-4, the study population will consist of adults aged 18-64 years and children aged 4-17 years with asthma. Study subjects must have spent a year in a traditional health plan with no or low deductibles prior to the switch to an HSA-HDHP with or without a PDL, and then remain enrolled for at least one year post-switch. Control group members spend a year in a traditional plan then remain in a traditional plan for at least another 12 months.