A number of promising new approaches for both local and systemic control of locally advanced non-small cell lung cancer have been examined in clinical trials, aimed at improving the patient survival. Development of better systemic therapies by adopting newer agents (such as epidermal growth factor receptor-tyrosine kinase inhibitors and immune checkpoint inhibitors) from advanced non-small cell lung cancer is mandatory. As for radiotherapy, adaptive radiotherapy and proton therapy are under investigation after the RTOG 0617 trial unexpectedly failed to show the efficacy of high-dose radiotherapy for Stage III disease. To date, no Phase III trial has clearly shown the benefit of adding surgery as a part of multimodality therapy for locally advanced non-small cell lung cancer. Such poor progress in the development of effective treatments for Stage III non-small cell lung cancer is considered to be attributable to the existence of heterogeneities in the disease characteristics, including the biological and anatomic characteristics. Constant effort via well-designed and well-conducted clinical trials is needed to decipher the heterogeneity of Stage III non-small cell lung cancer.