Objective Research has demonstrated that treating cancer patients' psychological and physical health leads to improved overall health. This may be especially true for palliative care patients facing serious illness. This study examines the proportion and determinants of psychology service utilization in an outpatient palliative care population. Methods Data from an existing clinical database in an outpatient palliative clinic utilizing a collaborative care model to deliver psychology services were explored. This study was framed by Andersen's Behavioral Model of Health Service Use, which incorporates three main components: predisposing, enabling, and need factors to model health service utilization. The sample (N=149) was majority middle aged, female, and White with a primary diagnosis of cancer. Cross-tabulations were conducted to determine how many patients who met screening criteria for depression or anxiety sought psychology services. Logistic regression analyses were conducted to assess for predisposing, enabling, and need factor determinants of psychology service utilization. Results Among patients who met criteria for moderate depression or anxiety, 50% did not access readily available psychology services. Enabling factors were the strongest determinant of psychology utilization. Factors associated with need for psychology services (i.e., emotional distress and psychological symptom burden) did not reach significance in determining psychology service use. Conclusions This study extends current knowledge about psychology utilization to palliative care outpatients receiving care within a collaborative care model. Directions for future research include further investigation of care models that optimize enabling strategies to enhance access to these services, and examination of patient-reported barriers to receiving this care. Copyright © 2013 John Wiley & Sons, Ltd.