The invention provides biomarkers and combinations of biomarkers useful in diagnosing lung diseases such as non-small cell lung cancer or reactive airway disease. The invention also provides methods of differentiating lung disease, methods of monitoring therapy, and methods of predicting a subject's response to therapeutic intervention based on the extent of expression of the biomarkers and combinations of biomarkers. Kits comprising agents for detecting the biomarkers and combination of biomarkers are also provided.