Underutilization of mental health services is prevalent in the U.S., and an understanding of utilization patterns can inform interventions to enhance treatment use. The current study investigated longitudinal associations between changes in mental health care utilization (MHCU) and Big Five personality traits. Data included three waves (4,658 adult participants) of the Midlife Development in the United States (MIDUS) study. 1,632 participants provided data at all three waves. Second-order latent growth curve models showed that MHCU level predicted an increase in emotional stability, and emotional stability level predicted a decrease in MHCU. Increases in emotional stability, extraversion, and conscientiousness predicted decreases in MHCU. These results indicate that personality is associated with MHCU over time and may inform interventions to increase MHCU.