Background: Aware of the importance of patient- and family-centered care (PFCC) within the stressful Neonatal Intensive Care Unit (NICU), parents with NICU experience in Alberta, Canada approached the healthcare system and identified the need to evaluate parents’ experiences with PFCC in the NICU. To address this parent-identified priority, the Neonatal Intensive Care Experience Reporting (NICER) Instrument is being co-developed. Methods: Parent partners co-lead the research team, working in partnership with researchers and NICU clinicians to make decisions and generate processes. Co-developing the NICER Instrument includes four phases: (1) Defining PFCC principles and establishing items; (2) validating item content; (3) pilot testing; and (4) assessing additional measurement properties. Results: The NICER Co-development Team defined five core principles of PFCC specific to the NICU and developed initial items (n=72) based on these principles. To validate item content, parent advisors (n=10), NICU clinicians (n=13), and PFCC researchers (n=10) rated the relevance of 72 items based on the NICU PFCC principles. The item content validity index (I-CVI) ranged from 0.54 to 1, and an I-CVI cut-off of 0.85 retained 51 items. Expert feedback and team discussion reduced the items to 49. Parent advisors (n=52) from NICU parent advisory groups in Alberta pilot tested 49 items which took an average of 14.71 minutes (SD=7.49) to complete. Feedback on item clarity, user friendliness, and instrument length was generally positive. Open-ended responses regarding item content and wording informed refinements prior to utilizing the NICER Instrument in NICUs. To further assess instrument reliability and validity, 400 family members across Alberta NICUs are currently being recruited to complete the NICER Instrument. Conclusion: This in-progress research demonstrates how family members, researchers, and clinicians can effectively co-develop a patient-reported measure to ensure that essential patient and family expertise is not overlooked when defining healthcare experiences and conceptualizing care evaluation.