This study examines the determinants of psychology service utilization among a chronically ill population. Data were combined from an outpatient palliative care clinic using two patient outcome studies for a secondary data analysis. Overall, 149 patients were examined with the majority being middle-aged (M = 55, SD = 14.73), female (n=112; 75.2%) and White (n=123; 82.6%) with a primary diagnosis of cancer (n=117; 78.5%) over a 37 month time period. Using the Behavioral Model of Health Service Use (Andersen, 1995), separate logistic regression analyses were conducted to assess for significant predisposing, enabling and need factor determinants of psychology service utilization in outpatient palliative care. The significant determinants from each of these factors were then modeled together. The total number of visits to see a palliative care physician was found to be the strongest determinant of psychology service utilization (p < .001). Seeing multiple providers was also a statistically significant determinant of psychology service utilization (p = .002) as well as not taking a non-opioid analgesic (p = .024). These findings suggest enabling factors from Andersen's model are most strongly associated with psychology service utilization in outpatient palliative care populations. Of note, many factors associated with need for psychology services, such as emotional distress, psychological symptom burden or having a psychological comorbidity, did not reach significance in determining psychology service use. These findings reinforce previous research that indicates chronically ill individuals are not likely to receive mental health care even though it is documented that they have increased distress related to their mental health. Also, these findings indicate the need for further investigation as to who is receiving referrals for psychology services, as it is noted in the scientific literature that many chronically ill individuals are under-recognized as needing mental health care referrals by their physicians.