This study proposes to systematically identify modifiable determinants of adherence in COPD based on the Theory of Self-Regulation in 360 patients with COPD. A novel and significant innovation of this study is the use of mobile health (mhealth) technology to objectively assess medication use. No previous study of self-regulation theory has utilized objective measure of adherence. A further innovation of the study is the use of ecological momentary assessment (EMA) of patient reported symptoms and beliefs to evaluate longitudinal associations between observation (patient symptoms) judgements (medication use to relieve symptoms), and reactions (self-efficacy, outcome expectancy, and medication beliefs) in real time. This study will be the first to objectively evaluate the application of the Self-Regulation Theory in COPD and to examine the long-term longitudinal impact of medication adherence on disease progression in a diverse sample.