This study examined the changes in outpatient palliative care services at US cancer centers over the past decade. Between April and August 2018, all National Cancer Institute (NCI)-designated cancer centers and a random sample of 1252 non-NCI-designated cancer centers were surveyed. Two surveys used previously in a 2009 national study were sent to each institution: a 22-question cancer center executive survey regarding palliative care infrastructure and attitudes toward palliative care and an 82-question palliative care program leader survey regarding detailed palliative care structures and processes. Survey findings from 2018 were compared with 2009 data from 101 cancer center executives and 96 palliative care program leaders. The overall response rate was 69% (140 of 203) for the cancer center executive survey and 75% (123 of 164) for the palliative care program leader survey. Among NCI-designated cancer centers, a significant increase in outpatient palliative care clinics was observed between 2009 and 2018 (59% vs 95%; odds ratio, 12.3; 95% confidence interval, 3.2-48.2; P < .001) with no significant changes in inpatient consultation teams (92% vs 90%; P = .71), palliative care units (PCUs; 26% vs 40%; P = .17), or institution-operated hospices (31% vs 18%; P = .14). Among non-NCI-designated cancer centers, there was no significant increase in outpatient palliative care clinics (22% vs 40%; P = .07), inpatient consultation teams (56% vs 68%; P = .27), PCUs (20% vs 18%; P = .76), or institution-operated hospices (42% vs 23%; P = .05). The median interval from outpatient palliative care referral to death increased significantly, particularly for NCI-designated cancer centers (90 vs 180 days; P = 0.01). Despite significant growth in outpatient palliative care clinics, there remain opportunities for improvement in the structures and processes of palliative care programs.