The Department of Health and Human Services, specifically the National Institutes of Health, is seeking proposals for the clinical validation of a candidate biomarker for neurological or neuromuscular disorders. Biomarkers are indicators of biological processes or responses to interventions, and they play a crucial role in the development of therapeutics and clinical care decisions. This solicitation aims to advance the validation of biomarkers for neurological and neuromuscular disorders through rigorous clinical validation of the biomarker detection method. The research should focus on one or two specified contexts of use and include evidence of preliminary testing and development of the detection method. The funding opportunity uses a cooperative agreement, milestone-driven mechanism, and the results may be used to support submissions to the FDA's Biomarker Qualification program. The application should include a clear study design, statistical design, and timeline, as well as collaborations with relevant experts. Rigor, reproducibility, data sharing, and intellectual property considerations are also emphasized. The funding priority will be given to applications that address unmet medical needs, have a strong biological rationale, and provide a justification for the utility of the biomarker in the clinical setting or clinical trial design.