Recent advances in imaging offer exciting opportunities to develop and validate lung-specific biomarkers as valuable adjuncts to diagnosis, tests of treatment efficacy, and/or treatment monitoring. State-of-the art structural, functional, and molecular imaging methods allow the lungs to be visualized non-invasively in vivo at sub-millimeter and sub-second spatial and temporal scales. However, the development and validation of imaging biomarkers presents some special challenges, including equipment evaluation, procedure standardization, data regarding reproducibility and replication, inter-rater variability, the production and measurement of reference standards, sensitivity to interventions or disease progression, inter-subject variance, choice of image reconstruction and segmentation algorithms, automated vs observer-dependent image analysis, data acquisition during conditions of standardized lung volume, whether a reliable association can be demonstrated between the imaging biomarker and a clinical endpoint, and whether its use will have a favorable cost-effective impact on drug development or disease management. Establishing such performance characteristics, especially for single investigators at single institutions, can be daunting if not impossible for costly biomarkers such as imaging. Therefore, to take full advantage of the opportunities presented by state-of-the-art imaging methods, new approaches to analytic and clinical validation must be developed in collaboration with industry, foundation, and federal funding agencies.