Background: Multiple stakeholders have called for the development of tools to facilitate values elicitation with patients to inform treatment decision making about chemotherapy. We previously developed a best-worst scaling (BWS) measure, a theory-driven values elicitation tool, for older adults (≥ 60 years) with blood cancers through patient and expert engagement. We sought to evaluate the feasibility and validity of using this measure to inform initial treatment decisions for newly-diagnosed patients. Methods: We completed a convergent mixed-methods study to test feasibility and validity of remote delivery of the measure following guidance for choice experiments (Janssen, Exp Rev Pharm Out Res, 2017). Convergent validity was evaluated by comparing preferences with a ranking exercise. Content validity was tested in cognitive interviews. Results: 178 patients at a public safety net hospital were eligible, 157 (88%) were approached, and 48 (31%) consented (48% lymphoma, 40% leukemia/myelodysplastic syndrome, 12% other). Mean age was 73.9 years (range 60 - 95). 59% were male; 96% were white; 67% had a bachelor’s degree or higher. 52% completed the BWS measure prior to their initial treatment visit. Patients agreed or strongly agreed that the instrument was understandable (96%), relevant to them (58%), and showed their real preferences (75%). 50% felt it was easy to answer. 54% of responses from the BWS measure were concordant with ranking on their top priority. Cognitive interviews (n=7) demonstrated content validity: all patients were able to accurately describe the instructions of the BWS instrument and correctly define each included outcome; most patients reported that the BWS instrument helped solidify their preferences; all patients reported it was beneficial; no patients reported missing domains of outcomes; all reported that the time and emotional burden to complete the measure were appropriate. Conclusions: Using this BWS measure to inform treatment decisions of older adults with newly-diagnosed blood cancers is feasible and appears valid for clinical use. Future work is needed to optimize implementation and validate the measure in different settings and with a larger and more diverse population.