Leptomeningeal carcinomatosis (LM) is an infrequent yet morbid and often fatal complication of non–small cell lung cancer (NSCLC). Management of LM is multimodal, often involving systemic chemotherapy, radiotherapy, and a variety of symptom management maneuvers to address elevated intracranial pressure, pain, and mood changes that can accompany the disease. It is increasingly recognized that tumors with actionable mutations in NSCLC, including epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) translocations, respond well to systemic therapy with tyrosine kinase inhibitors yet often progress in the central nervous system. More information is needed regarding the natural history and optimal management of LM in specific molecular subtypes of NSCLC. This case report summarizes the management of a patient with ALK-positive NSCLC who developed LM while on targeted treatment with crizotinib within the context of current NCCN Clinical Practice Guidelines in Oncology and recently published studies.