Each funding agency establishes its own set of procedures to guide the conduct of a rigorous and comprehensive review of proposals. Review procedures can differ across agencies and even for each competition sponsored by an agency. Foundations may establish special review panels for each competition, have members of their board review applications, or seek expertise from the scientific community on an ad hoc basis. Exceptions to this are made for special funding opportunities such as supplementary or discretionary funding, minority supplement awards, or certain fellowships. This chapter discusses the most common review process, the peer-review system used by the Public Health Service (PHS), which includes the National Institutes of Health (NIH) and the Agency for Healthcare Research and Quality. The chapter also looks at review criteria, scores, and categories of acceptance and rejection.