This paper is a report of a study of the Assistance, Support, and Self-health Initiated through Skill Training (ASSIST) randomized control trial. The aim of this paper is to understand whether participating in ASSIST significantly changed the out-of-pocket (OOP) costs for family caregivers of Alzheimer's disease (AD) or Parkinson's disease (PD) patients.Secondary analysis of randomized control trial data, calculating average treatment effects of the intervention on OOP costs. Enrollment in the ASSIST trial occurred between 2002 and 2007 at 2 sites: Durham, North Carolina, and Birmingham, Alabama. We profile OOP costs for caregivers who participated in the ASSIST study and use 2-part expenditure models to examine the average treatment effect of the intervention on caregiver OOP expenditures.ASSIST-trained AD and PD caregivers reported monthly OOP expenditures that averaged $500-$600. The intervention increased the likelihood of caregivers spending any money OOP by 26 percentage points over usual care, but the intervention did not significantly increase overall OOP costs.The ASSIST intervention was effective and inexpensive to the caregiver in direct monetary outlays; thus, there are minimal unintended consequences of the trial on caregiver financial well-being.