Background: National Consensus Project for quality palliative care guidelines emphasizes the importance of a comprehensive assessment of all care domains, including physical, psychosocial, and spiritual aspects of care, for seriously ill patients. However, less is known about how real-world practice compares with this guideline. Objective: To describe clinicians' assessment practices and factors influencing their approach. Design: This is a two-part web-based survey of palliative care clinicians from five academic groups in the United States. Results: Nineteen out of 25 invited clinicians (physicians, nurse practitioners, and physician assistants) completed the survey. A majority (62%) reported that, although some elements of assessment were mandatory, their usual practice was to tailor the focus of the consultation. Time limitations and workload received the highest mean scores as reasons for tailored assessment (6.1 on a 0-9 importance scale), followed by beliefs that comprehensive assessment is unnecessary (4.8) and absence of the full interdisciplinary team (4.4). All participants cited symptom acuity, and 91% cited reason for consult as factors influencing a tailored approach. Among domains "always" assessed, physical symptoms were reported most commonly (81%) and spiritual and cultural factors least commonly (24% and 19%, respectively). Although a majority of clinicians reported usually tailoring their consultations, mean importance scores for almost all assessment elements were high (range 3.9-8.8, mean 7.1); however, there was some variation based on reason for consult. Spiritual elements received lower importance scores relative to other elements (5.0 vs. 7.4 mean score for all others). Conclusion: Although clinicians placed high importance on most elements included in comprehensive palliative care, in practice they often tailored their consultations, and the perceived relative importance of domains shifted depending upon the type of consultation.