Background Bronchiectasis is associated with loss of lung function, substantial use of health care resources, and increased morbidity and mortality in people with cardiopulmonary diseases. Purpose To assess the frequency and severity of bronchiectasis and related clinical findings of participants in a low-dose CT (LDCT) screening program. Materials and Methods The Early Lung and Cardiac Action Program (ELCAP) bronchiectasis score (range, 0-42; higher values indicate more severe bronchiectasis) was developed to facilitate bronchiectasis assessment. This quantitative scoring system screened participants based on accumulated knowledge and improved CT imaging capabilities. Secondary review of LDCT studies from smokers aged 40-90 years was performed when they were initially enrolled in the prospective Mount Sinai ELCAP screening study between 2010 and 2019. Medical records were reviewed to identify associated respiratory symptoms and acute respiratory events during the 2 years after LDCT. Logistic regression analysis was performed to examine factors associated with bronchiectasis. Results LDCT studies of 2191 screening participants (mean age, 65 years ± 9; 1140 [52%] women) were obtained, and bronchiectasis was identified in 504 (23%) participants. Median ELCAP bronchiectasis score was 12 (interquartile range, 9-16). Bronchiectasis was most common in the lower lobes for all participants, and lower lobe prevalence was greater with higher ELCAP score (eg, 91% prevalence with an ELCAP score of 16-42). In the fourth quartile, however, midlung involvement was higher compared with lower lung involvement (128 of 131 participants [98%] vs 122 of 131 participants [93%]). Bronchiectasis was more frequent with greater age (odds ratio [OR] = 2.0 per decade; 95% CI: 1.7, 2.4); being a former smoker (OR = 1.33; 95% CI: 1.01, 1.73); and having self-reported chronic obstructive pulmonary disease (OR = 1.38; 95% CI: 1.02, 1.88), an elevated hemidiaphragm (OR = 4; 95% CI: 2, 11), or consolidation (OR = 5; 95% CI: 3, 11). It was less frequent in overweight (OR = 0.7; 95% CI: 0.5, 0.9) or obese (OR = 0.6; 95% CI: 0.4, 0.8) participants. Two years after baseline LDCT, respiratory symptoms, acute respiratory events, and respiratory events that required hospitalization were more frequent with increasing severity of the ELCAP bronchiectasis score (P < .005 for all trends). Conclusion Prevalence of bronchiectasis in smokers undergoing low-dose CT screening was high, and respiratory symptoms and acute events were more frequent with increasing severity of the Early Lung and Cardiac Action Program Bronchiectasis score. © RSNA, 2022 See also the editorial by Verschakelen in this issue.