Background: Patients with hematologic malignancies have unmet palliative care needs but are less likely to receive specialist palliative care services than patients with solid tumors. This difference is poorly understood. Methods: Multisite, mixed-methods study to understand and contrast perceptions of palliative care among hematologic oncologists and solid tumor oncologists. Between February and October 2012, oncologists at 3 academic medical centers with well-established palliative care services completed surveys assessing referral practices and in-depth, semi-structured interviews about their views of palliative care. We compared referral patterns using standard statistical methods. We then analyzed qualitative interview data using constant comparative methods to explore reasons for observed differences. Results: Among 66 interviewees, 23 oncologists cared exclusively for patients with hematologic malignancies, and 43 treated only patients with solid tumors. Seven of 23 hematologic oncologists (30%) reported never referring a patient to palliative care; all solid tumor oncologists had previously referred (p<0.001). In qualitative analyses, most hematologic oncologists viewed palliative care as end-of-life care, while most solid tumor oncologists viewed palliative care as a subspecialty that could assist with complex cases and/or offload burden in a busy clinic. Solid tumor oncologists emphasized practical barriers to palliative care referral, such as appointment availability and reimbursement issues. Hematologic oncologists emphasized philosophical concerns about palliative care referrals, including different treatment goals, responsiveness to chemotherapy, and a preference to control palliative aspects of patient care. Conclusions: Most hematologic oncologists view palliative care as end-of-life care, while solid tumor oncologists more often view palliative care as a subspecialty for co-managing complex patients. Efforts to integrate palliative care into hematologic malignancy practices will require solutions that address unique barriers to palliative care referral experienced by hematologic oncologists.