Prognostication has been described as "Medicine's Lost Art." Taken with diagnosis and treatment, prognostication is the third leg on which medical care rests. As research leads to additional beneficial treatments for vexing conditions like cancer, dementia, and lung disease, prognostication becomes even more difficult. This article, written by a group of palliative care clinicians with backgrounds in geriatrics, pulmonology, and oncology, aims to offer a useful framework for consideration of prognosis in these conditions. This article will serve as the first in a three-part series on prognostication in adults and children.