Background: Clinical trials have shown that collecting electronic patient-reported outcomes (ePROs) improves quality of life and survival in cancer patients. To bolster integration of ePROs into routine care, the SIMPRO Research Consortium developed an electronic symptom management (eSyM) program, deployed it at six cancer centers, and conducted a hybrid effectiveness-implementation study. eSyM, an ePRO toolkit integrated into the Epic EHR, enables patients to report and care teams to triage symptoms in real-time. To assess eSyM, we conducted structured qualitative interviews with patients and clinic staff, including doctors, nurses, advanced practice providers, and administrative staff. We sought to understand eSyM from the patient and staff perspectives. Methods: Using an iterative process, we developed semi-structured interview guides to query the experiences and perceptions of patients and staff exposed to eSyM. Questions were informed by the Consolidated Framework for Implementation Research. One year after eSyM was launched, sites identified and referred participants for interviews or focus groups. Participants must have either used eSyM to submit symptoms (patients) or had access to eSyM at their institution (staff). Patients provided written consent; a consent waiver was obtained for staff. Interviews were recorded and transcribed, and a common analytic codebook was developed. Transcripts were dual or triple-coded and underwent thematic analysis to identify key contexts and concepts within and across patient and staff groups. Results: From 9/28/20 to 4/14/23, 50 staff participated in individual interviews and 29 participated in focus groups (79 total). From 9/14/23 to 3/14/24, 14 patient interviews were conducted. Transcripts revealed that staff and patients held similar beliefs regarding eSyM compatibility, communication, and prioritization. 93% (13/14) of patients and 72% (57/79) of staff believed eSyM was easy to use and improved communication. Both cohorts (66% staff, 36% patients) noted that competing demands often needed to be prioritized over responding to symptom concerns. Discordance emerged in the domains of receptivity and technology; patients were more receptive and capable of using eSyM than staff perceived. Both groups believed eSyM was helpful but perceived that deeper engagement from patients and staff was necessary for sustainability. Conclusions: Most interviewees reported that eSyM added value and was easy to navigate. Competing clinical demands, however, frequently deprioritized use of eSyM. Staff tended to underestimate patients’ receptivity to use eSyM and were more likely to cite competing demands as a barrier to their own use of eSyM. Sites looking to adopt eSyM, or similar ePRO programs, will benefit from understanding the facilitators that need to be incorporated and the barriers that need to be surmounted to optimize success. Clinical trial information: NCT03850912.