Local failure of non-small-cell lung cancer (NSCLC) radiotherapy may cause continuous tumor seeding and death. Radiotherapy dose escalation has been shown to improve local control and survival. However, the toxicities associated with dose escalation are significant and limit the potential of dose escalation. Intensity modulated radiotherapy (IMRT) may have the potential to improve the therapeutic ratio for photon treatment of lung cancer by sparing surrounding normal tissues. However, low-dose exposure to normal lung and organ motion is a major concern. We have conducted several studies to address these issues and started clinical studies to evaluate the potential benefit of IMRT in patients with NSCLC. Proton radiotherapy may have greater potential to spare normal tissue and allow for further dose escalation and acceleration. We are conducting preclinical and clinical studies for imaging-guided proton radiotherapy in NSCLC. In this paper, we discuss the preliminary data, IMRT treatment guidelines, and ongoing studies for proton therapy in NSCLC.