Advances in the treatment and prevention of asthma have curtailed deaths, hospitalizations, and increases in prevalence rates during the past 30 years.1 Nevertheless, the effectiveness of long-term asthma management is mediated by behavioral factors, such as adherence to medication and psychosocial stress. In a study using ecological momentary assessment (EMA) to monitor asthma inhaler use, half of all nonadherence cases occurred while partici- pants were with their peers.2 However, the study relied on sub- jective reports of adherence. Associations between stress and asthma symptoms have been observed, but these associations have relied on retrospective self-report, potentially introducing recall bias. Laboratory studies have found causal associations between stress and biological markers of immune responses related to asthma.3,4 However, these settings may not represent real-world situations. Furthermore, both laboratory and longitudinal studies to date have not captured the effect of daily variations in adherence, stress, and symptoms.