Delirium has the highest occurrence rate of any complication in hospitalized adults over the age of 65. The study objective was to determine physician information needs for use in the development of electronic clinical decision support for physicians managing the care of patients with delirium. Critical incident interviews were conducted with 8 experienced internal medicine physicians and 1 cardiologist. Thematic analysis revealed the following 6 themes: 1) Clinician's experience an impoverished information field for mental status, 2) Uncertainty is pervasive, 3) Extensive information foraging effort is required for cohesive story building, 4) Goal Conflict leads to missed diagnosis and early closure, 5) Diffusion of Responsibility for treating delirium is common, and 6) Use of structured delirium resources is minimal. Elicited information needs were identified and physician recommendations for improving access to information needed in managing the care of patient's with delirium are reported. Information elicited in this study is useful for designing delirium clinical decision support that supports physician cognition.