Introduction: Frailty is a state of vulnerability, and may go unrecognized in emergency medical services (EMS). Identifying frailty earlier may allow for services to be offered proactively to maintain function and prevent further health deterioration. The Clinical Frailty Scale (CFS) can be used to screen for frailty, but has only been validated when used by physicians. Our objective was to evaluate the feasibility and validity of a Care Partner-completed CFS, facilitated by a paramedic or nurse. Methods: A prospective sample of older adults (age ≥ 70 years) presenting in two settings (to EMS, following a 911 call, and to Geriatric Ambulatory Care) between February 2009 and March 2010 were included. Care partners completed a survey that included the nine-point CFS, which grades from 1 (very fit) to 9 (terminally ill). Demographic, clinical and outcome data were collected from the health care record, with one year follow-up. Based on clinical evaluations a frailty index was calculated for each patient. In each setting, descriptive statistics were used to compare fitter patients (CFS scores <5) to frailer ones (CFS scores >4). Results: The mean age was 82.2 ± 5.9 years (n=198) and most were women (n = 118, 62.1%). The Care Partner-CFS was incomplete for 3 surveys. The median CFS score in both the clinic and EMS groups was 5 (interquartile range = 4-6). The Care Partner-CFS correlated moderately with their independently assessed frailty index (0.64; p<0.01; n=195). Most patients (n=125; 64%) had frailty scores > 4. Frail patients were older and had worse health outcomes than the patients with score <5. More EMS patients were severely frail or very severely frail compared to the geriatric clinic patients (n = 19, 19% vs. n =5, 5%). Conclusion: The Care Partner-CFS is a feasible and valid method for evaluating frailty in the EMS and medical clinic settings where frailty was common. It may be a useful EMS screening tool to identify those that could benefit from comprehensive assessment and follow-up after emergency care. Future research will evaluate this approach in multiple populations with community based follow-up intervention for those at higher risk.