Background: Electronic cigarettes (e-cigarettes) are battery-operated nicotine-delivery devices used by some smokers as a cessation tool as well as by never smokers. Objective: To determine the usage of e-cigarettes in older adults at risk for or with chronic obstructive pulmonary disease (COPD). Design: Prospective cohorts. Participants: COPDGene (N = 3536) and SPIROMICS (N = 1060) subjects who were current or former smokers aged 45–80. Main Measures: Participants were surveyed to determine whether e-cigarette use was associated with longitudinal changes in COPD progression or smoking habits. Key Results: From 2010 to 2016, participants who had ever used e-cigarettes steadily increased to 12–16%, but from 2014 to 2016 current use was stable at ~5%. E-cigarette use in African-Americans (AA) and whites was similar; however, AA were 1.8–2.9 times as likely to use menthol-flavored e-cigarettes. Current e-cigarette and conventional cigarette users had higher nicotine dependence and consumed more nicotine than those who smoked only conventional cigarettes. E-cigarette users had a heavier conventional cigarette smoking history and worse respiratory health, were less likely to reduce or quit conventional cigarette smoking, had higher nicotine dependence, and were more likely to report chronic bronchitis and exacerbations. Ever e-cigarette users had more rapid decline in lung function, but this trend did not persist after adjustment for persistent conventional cigarette smoking. Conclusions: E-cigarette use, which is common in adults with or at risk for COPD, was associated with worse pulmonary-related health outcomes, but not with cessation of smoking conventional cigarettes. Although this was an observational study, we find no evidence supporting the use of e-cigarettes as a harm reduction strategy among current smokers with or at risk for COPD.