Adult day services (ADS) aim to help elders age in place, but evidence of impact on participants lags behind caregiver research. To play a larger role in the continuum of care, ADS participant outcomes should regularly be documented with standard measures. We conducted a Delphi review of one integrated participant assessment system. Capturing physical, mental, and cognitive health indicators and activity engagement of typical ADS participants (i.e., frail elders eligible for nursing home placement), experts evaluated the system on instrument validity, relevance, and application. Practitioners and researchers completed multiple assessments of the system’s instruments and alternatives. Finally, panelists addressed the potential benefits and challenges of system adoption by ADS providers. Panelists concurred that such a system would benefit individuals, families, and providers; concerns related to cost and staffing requirements and appropriateness for distinct client populations. A refined system can reveal best practices to enhance ADS service delivery and participant outcomes.