We propose here to develop pure HCV antigens and a standardized immunoassay for quantification of anti-HCV antibody responses to vaccination, and to develop a standardized HCV neutralization panel with genetically and phenotypically diverse viruses for quantification of neutralizing antibody responses to vaccination. These reference panels could be adopted as a standard for measurement of antibody titers and neutralizing breadth, which would allow meaningful comparisons of results obtained in different laboratories, and more rapid advancement of HCV vaccine development. Development of an HCV vaccine is an urgent priority. Accurate and standardized measurement of the titers, neutralizing potency and breadth of antibodies using diverse HCV isolates is key to evaluating HCV vaccine candidates and comparing results obtained in different laboratories. By generation of pure HCV antigens, a standardized immunoassay, and a standardized neutralization panel, we will facilitate accurate, reproducible measurements of antibody responses, and accelerate HCV vaccine development.