Assessment is a critical aspect of treatment planning, and while there exist standards for facilitating music therapy assessments in a variety of clinical settings, no such standards exist for music therapists in hospice and palliative care. This gap in knowledge, which limits music therapists’ ability to provide patients and caregivers best practices promoting supported movement through the dying process, becomes particularly problematic when assessing patients who are imminently dying with a 24–72 hour prognosis. To further develop and define assessment and clinical decision-making processes used by music therapists in hospice and palliative care, the authors used a constructivist grounded theory and situational analysis methodology to analyze interviews of 15 hospice music therapists. The resulting theoretical model describes an ongoing process of assessment and clinical decision-making shaped by participants’ individual epistemologies. Epistemologies were comprised of 5 ways of knowing, which were termed experiential, personal, musical, ethical, and integral, and provided participants critical foundations for their practice. The results support a development of a model for reflective practice as well as continued research on epistemological foundations of clinical practice.