Background: Investigators have tested interventions delivered by specialty palliative care (SPC) clinicians, or by clinicians without palliative care specialization (primary palliative care, PPC). Objective: To compare the characteristics and outcomes of randomized clinical trials (RCTs) of SPC and PPC interventions. Design: Systematic review secondary analysis. Setting/Subjects: RCTs of palliative care interventions. Measurements: Interventions were classified SPC if delivered by palliative care board-certified or subspecialty trained clinicians, or those with extensive clinical experience; all others were PPC. We abstracted data for each intervention: delivery setting, delivery clinicians, outcomes measured, trial results, and Cochrane's Risk of Bias. We conducted narrative synthesis for quality of life, symptom burden, and survival. Results: Of 43 RCTs, 27 tested SPC and 16 tested PPC interventions. SPC interventions were more comprehensive (4.2 elements of palliative care vs. 3.1 in PPC, p = 0.02). SPC interventions were delivered in inpatient (44%) or outpatient settings (52%) by specialty physicians (44%) and nurses (44%); PPC interventions were delivered in inpatient (38%) and home settings (38%) by nurses (75%). PPC trials were more often of high risk of bias than SPC trials. Improvements were demonstrated on quality of life by SPC and PPC trials and on physical symptoms by SPC trials. Conclusions: Compared to PPC, SPC interventions were more comprehensive, were more often delivered in clinical settings, and demonstrated stronger evidence for improving physical symptoms. In the face of SPC workforce limitations, PPC interventions should be tested in more trials with low risk of bias, and may effectively meet some palliative care needs.