© JNCCN - Journal of the National Comprehensive Cancer Network. These NCCN Guidelines Insights focus on recent updates to the 2015 NCCN Guidelines for Non-Small Cell Lung Cancer (NSCLC). Appropriate targeted therapy is very effective in patients with advanced NSCLC who have specific genetic alterations. Therefore, it is important to test tumor tissue from patients with advanced NSCLC to determine whether they have genetic alterations that make them candidates for specific targeted therapies. These NCCN Guidelines Insights describe the different testing methods currently available for determining whether patients have genetic alterations in the 2 most commonly actionable genetic alterations, notably anaplastic lymphoma kinase (ALK) gene rearrangements and sensitizing epidermal growth factor receptor (EGFR) mutations.