This issue of Critical Care Clinics, Guest Edited by Dr. Stephen M. Pastores and Dr. Wendy R. Greene, focuses on Critical Care of the Cancer Patient (Pastores) and Geriatric Critical Care (Greene). Dr. Pastores' section of the issue is devoted to Critical Care of the Cancer Patient and includes the following topics: Triage and Prognostication of Cancer Patients Admitted to the ICU; ICU Organization and Interdisciplinary Care for Critically Ill Patients with Cancer; Critical Care of the Hematopoietic Stem Cell Transplant Recipient; Management of Drug Toxicities; Acute Kidney Injury in the Critically Ill Patient with Cancer; Infectious Disease Complications in Cancer Patients; and Palliative, Ethics, and End-of-Life Care Issues in the Cancer Patient. Dr. Green's section of the issue, devoted to Geriatric Critical Care, includes the following topics: The effect of aging physiology on critical care; The frailty syndrome: a critical issue in geriatric oncology; Detection of delirium in the intensive care unit: comparison of confusion assessment method for the intensive care unit with confusion assessment method ratings; Evidence-based geriatric nursing protocols for best practice; The effect of dementia in the critically ill geriatric patient; Nutritional assessment: a primary component of multidimensional geriatric assessment in the ICU; Rehabilitation concerns in the geriatric critically ill and injured; and Geriatric palliative care.