Statement of Purpose: Pediatric firearm access is a significant risk factor for unintentional injury and suicide. This study investigated parents' perspectives on an adapted firearm safety program, "S.A.F.E. Firearm," to ensure acceptability and optimize effectiveness prior to the launch of an upcoming hybrid effectiveness-implementation trial. Methods/Approach: We administered a cross-sectional survey with a convenience sample of U.S. parents to measure the acceptability of "S.A.F.E. Firearm" and other key variables (e.g., relationship with pediatrician) that may impact our implementation approach. The sample included 97 participants (52 firearm-owning and 45 non-owning) from across the country. We also conducted semi-structured interviews using a Think Aloud exercise with 11 survey participants that were analyzed with directed content analysis. Results: The mean acceptability score was 4.35 [SD 0.52] on a 1-5 Likert scale, indicating that participants viewed S.A.F.E. Firearm as highly acceptable. Most participants (84%) either agreed or completely agreed with recommending that a friend receive "S.A.F.E. Firearm." No significant differences in acceptability scores were found by firearm ownership status, gender, race and ethnicity, or region of residence. Parent-pediatrician depth of relationship was associated with acceptability (r= 0.21, p=0.038). Interviews indicated that a collaborative approach to decision-making, neutral messaging, and provision of tangible resources were key factors that contributed to the program's overall high acceptability scores. Conclusion & Significance: The present study served as the final check in our process of adapting an evidence-based safe firearm storage program to increase reach and effectiveness as a universal suicide prevention strategy in pediatric primary care. Convergent parent feedback confirms that "S.A.F.E. Firearm" is highly acceptable and ready for implementation. Moreover, our findings suggest that family-centeredness may be enhanced through explicit integration of parents' needs and preferences into program refinements. Use of qualitative Think Aloud exercises with end user groups can add value when actual implementation of firearm safety programs can only be approximated.