Despite growing awareness of the substantial burden of long-term pulmonary impairment among tuberculosis survivors, marked variability in how post-tuberculosis lung disease is defined across research studies limits the comparison of findings and synthesis of evidence. To facilitate greater harmonisation within the field, we propose a case definition for post-tuberculosis lung disease for use in research studies. Conceptual aspects of this case definition were initially developed with input from a broad group of stakeholders at the 2nd International Post-Tuberculosis Symposium and were refined by the authors after the Symposium. Guiding principles for the definition include specificity, feasibility in settings with high tuberculosis disease burdens, probable relevance to long-term health outcomes, and applicability across the lifespan. The definition is designed to be used alongside, rather than instead of, study-specific definitions used to explore primary study hypotheses, and is accompanied by a reporting framework. The case definition has three components: that the individual had previous pulmonary or pleural tuberculosis disease and does not have tuberculosis disease at the time of evaluation; that the individual has, at the time of assessment, evidence of pulmonary disease with abnormalities in at least two of three clinical domains of lung function, respiratory symptoms, and chest imaging; and that the pulmonary disease manifestations should be attributable at least in part to previous tuberculosis disease. This definition is developed in the absence of data on long-term patient outcomes and will need to evolve over time in response to emerging evidence. However, we believe this proposed definition will lead to greater consistency and rigor across studies of post-tuberculosis lung disease with the goal of improving care and quality of life for millions of tuberculosis survivors worldwide.