Methods and compositions are provided for the molecular subtyping of lung cancer samples. Specifically, a method of assessing whether a patient's lung cancer subtype is adenocarcinoma, squamous cell carcinoma, or a neuroendocrine (encompassing both small cell carcinoma and carcinoid) is provided herein. A method for assessing whether a patient's lung cancer subtype is adenocarcinoma, squamous cell carcinoma, small cell carcinoma or carcinoid lung cancer is also provided. The methods provided herein entail probing the levels of the classifier biomarkers of Table 1-Table 6 or a subset thereof at the nucleic acid level, in a lung cancer sample obtained from the patient. Based in part on the levels of the classifier biomarkers, the lung cancer sample is classified as a particular lung cancer subtype.