Many older adults in the United States receive invasive medical care near the end of life, often in an intensive care unit (ICU). However, most older adults report preferences to avoid this type of medical care and to prioritize comfort and quality of life near death. We propose a novel term, “clinical momentum,” to describe a system-level, latent, previously unrecognized property of clinical care that may contribute to the provision of unwanted care in the ICU. The example of chronic critical illness illustrates how clinical momentum is generated and propagated during the care of patients with prolonged illness. The ICU is an environment that is generally permissive of intervention, and clinical practice norms and patterns of usual care can promote the accumulation of multiple interventions over time. Existing models of medical decision-making in the ICU describe how individual signs, symptoms, or diagnoses automatically lead to intervention, bypassing opportunities to deliberate about the value of an intervention in the context of a patient's likely outcome or treatment preferences. We hypothesize that clinical momentum influences patients, families, and physicians to accept or tolerate ongoing interventions without consideration of likely outcomes, eventually leading to the delivery of unwanted care near the end of life. In the future, a mixed-methods research program could refine the conceptual model of clinical momentum, measure its impact on clinical practice, and interrupt its influence on unwanted care near the end of life.