PURPOSE: In patients with lung cancer, dyspnea is one of the most prevalent and disabling symptoms, for which effective treatments are lacking. We examined the efficacy of a nurse-led brief behavioral intervention to improve dyspnea in patients with advanced lung cancer. METHODS: Patients with advanced lung cancer reporting at least moderate breathlessness (n = 247) were enrolled in a randomized trial of a nurse-led two-session intervention (focused on breathing techniques, postural positions, and fan therapy) versus usual care. At baseline and weeks 8 (primary end point), 16, and 24, participants completed measures of dyspnea (Modified Medical Research Council Dyspnea Scale [mMRCDS]; Cancer Dyspnoea Scale [CDS]), quality of life (Functional Assessment of Cancer Therapy-Lung [FACT-L]), psychological symptoms (Hospital Anxiety and Depression Scale), and activity level (Godin-Shephard Leisure Time Physical Activity Questionnaire). To examine intervention effects, we conducted analysis of covariance and longitudinal mixed effects models. RESULTS: The sample (Age = 66.15 years; 55.9% female) primarily included patients with advanced non-small cell lung cancer (85.4%). Compared with usual care, the intervention improved the primary outcome of patient-reported dyspnea on the mMRCDS (difference = -0.33 [95% CI, -0.61 to -0.05]) but not the CDS total score at 8 weeks. Intervention patients also reported less dyspnea on the CDS sense of discomfort subscale (difference = -0.59 [95% CI, -1.16 to -0.01]) and better functional well-being per the FACT-L (difference = 1.39 [95% CI, 0.18 to 2.59]) versus the control group. Study groups did not differ in overall quality of life, psychological symptoms, or activity level at 8 weeks or longitudinally over 24 weeks. CONCLUSION: For patients with advanced lung cancer, a scalable behavioral intervention alleviated the intractable symptom of dyspnea. Further research is needed on ways to enhance intervention effects over the long-term and across additional outcomes.