Background Spiritual well‐being is an important dimension of quality of life (QOL) and is a core component of quality oncology and palliative care. In this analysis, we aimed to describe spiritual well‐being outcomes in a National Cancer Institute (NCI)‐supported Program Project that tested the effectiveness of an interdisciplinary palliative care intervention in lung cancer patients and their family caregivers (FCGs). Methods Patients undergoing treatments for NSCLC and their FCGs were enrolled in a prospective, quasi‐experimental study. Patients and FCGs in the intervention group were presented at interdisciplinary care meetings and received four educational sessions that included one session focused on spiritual well‐being. Spiritual well‐being for patients was measured using the FACIT‐Sp‐12, and FCG spiritual well‐being was measured using the COH‐QOL‐FCG spiritual well‐being subscale. Multivariate analysis of covariance was undertaken for subscale and item scores at 12 weeks, controlling for baseline, by religious affiliations (yes or no) and group assignment. Results Religiously affiliated patients reported better scores in the Faith subscale and items on finding strength and comfort in faith and spiritual beliefs compared to non‐affiliated patients. Non‐affiliated patients had better scores for feeling a sense of harmony within oneself. By group, patients who received the intervention had significantly better scores for the Meaning/Peace subscale. Conclusions Our findings support the multidimensionality of spiritual well‐being that includes constructs such as meaning and faith for lung cancer patients and FCGs with or without religious affiliations. Palliative care interventions should include content that targets the spiritual needs of both patients and FCGs. Copyright © 2015 John Wiley & Sons, Ltd.