Objectives Describe the use of a Symptom Assessment (SA) Toolkit designed to support in-home caregivers of homebound older adults with serious illness. Explore next steps in evaluation and dissemination of the Toolkit. Importance. Many older adults with serious illness who depend on others for care have symptoms that are difficult to manage. Supporting in-home caregivers in symptom assessment (SA) may improve suffering among older adults. Objective(s). To test the feasibility of a SA-Toolkit for caregivers to assess and track older adults' symptoms. Method(s). With multi-stakeholder input, we created a SA-Toolkit consisting of illustrations depicting symptoms, a validated 5-faces severity scale, and an easy-touse tracking system with phone numbers of family/ friends/clinicians to contact if symptoms worsened. We recruited English-speaking patients $65 years old and their caregivers from a home-based geriatrics program in San Francisco. Using validated questionnaires at baseline and 1-week, we assessed patients' symptoms, patients' and clients' self-efficacy with SA (5- point Likert scale), and acceptability (i.e., recommend to others). We used Wilcoxon signed-rank tests. Results. Eleven patient-caregiver dyads participated. Patients were 84.7 years old (SD 5.7), 81.8% women, and 27.3% non-white. From baseline to 1-week, the mean number of symptoms decreased (3.7 (1.5) at baseline to 2.6 (1.8) at follow-up, p¼0.03). Specifically, the number of patients with pain decreased from 63.6% to 36.4%, anxiety 54.6% to 18.2%, depression 45.5% to 27.3%, and loneliness 36.4% to 18.2%. Caregiver self-efficacy increased (4.6 (0.3) to 4.8 (0.3), p¼0.09). Patients found the symptom illustrations easy-to-use (8.7 on 10-point scale), but the faces scale less so (7.3/10) because it provided ''too many choices.'' Caregivers liked the SA-Toolkit because it was ''easy to use''; nearly all (10/11, 90%) would recommend it to others. Suggested improvements included personalizing materials according to patients' symptoms. Conclusion(s). The SA-Toolkit resulted in decreased symptom burden among patients and higher caregiver self-efficacy in symptom assessment. Acceptability of the Toolkit was high among both patients and caregivers. Impact. A SA-Toolkit is feasible and may help reduce suffering in frail, older patients.