Currently, more than one third of Ontarians with a rare disease lack a genetic diagnosis, despite lengthy and costly investigations. Fortunately, genome-wide sequencing (GWS), in the form of exome sequencing (ES) and genome sequencing (GS), has transformed our ability to achieve a timely diagnosis for rare disease patients. Prior to April 2021, clinical GWS for Ontario patients was only available via an exceptional access program (EAP) and completed in laboratories outside Canada. The EAP program was designed as a ‘safety net’, rather than a regular service delivery model, and presented significant challenges including lack of oversight of turnaround time, diagnostic yield and impact, timing, and outcome of exome vs. genome. To address these challenges, CHEO and The Hospital for Sick Children (SickKids), in collaboration with the Ontario Ministry of Health, developed and is delivering an optimized clinical GWS service as a two-year pilot for individuals with rare diseases that is equitable, accessible, sustainable and performed in Ontario. The pilot project will provide GWS in the form of both ES (n=325 trios) and GS (n=325 trios) to 650 families from CHEO and SickKids. This work will enable robust assessment of diagnostic utility, cost effectiveness, and timeliness of ES and GS to inform provincial and cross-provincial policy related to the long-term organization, delivery, and reimbursement of genome-based diagnostics for rare disease.