A growing body of evidence and experience has effaced what were once thought to be clear distinctions between "critical illness" and "terminal illness" and has exposed the problems of postponing palliative care for intensive care patients until death is obviously imminent. Integration of palliative care as a component of comprehensive intensive care is now seen as more appropriate for all critically ill patients, including those pursuing aggressive treatments to prolong life. At present, however, data on which to base practice in this integrated model remain insufficient, and forces of the healthcare economy and other factors may constrain its application. The purpose of this article is to map where we are now in seeking to improve palliative care in the intensive care unit. We review existing evidence, which suggests that both symptom management and communication about preferences and goals of care warrant improvement and that prevailing practices for limitation of life-sustaining treatments are inconsistent and possibly irrational. We also address the need for assessment tools for research and quality improvement. We discuss recent initiatives and ongoing obstacles. Finally, we identify areas for further exploration and suggest guiding principles.