To begin the selection process, the PERCH investigators conducted an extensive review of the microbiologic diagnosis of respiratory infections. Using published and unpublished data, as well as user and developer experiences, our team prepared a strategic summary of the available technologies that could detect pathogens from respiratory tract specimens. We evaluated each major assay category, including traditional bacteriology and viral culture, direct antigen and immunofluorescent antibody detection, and nucleic detection acid tests. It was evident that molecular diagnostics should be among the mix of diagnostic tools required to meet the needs of PERCH.