Activating mutations in the epidermal growth factor receptor gene and rearrangement of the anaplastic lymphoma kinase gene exemplify the molecular characterization of nonsmall cell lung cancer (NSCLC), particularly adenocarcinoma, and its therapeutic relevance. Several genetic alterations with prognostic and predictive role, including ROS, RET, MET, KRAS, have now been identified in adenocarcinoma and some such as DDR2 and fibroblast growth factor receptor 1 in squamous cell carcinoma. This has heralded the development of agents targeted against these aberrations. Better knowledge of tumor biology and development of targeted agents has ushered an era of personalized treatment strategies in NSCLC, leading to improvements not only in tumor control and duration of life but also in quality of life.