Designed to be a useful desk reference. The first paper critically reviews the developments in infrared quantitative analysis through the year 1984. The next two papers are heavily applications-oriented to petroleum and synthetic polymers. Three papers focus on the use of computerized techniques to carry out multicomponent analysis by infrared methods. One presents the essential aspects of using factor analysis in quantitative spectroscopic applications. The final paper emphasizes the need for caution and crosschecking in the use of computers for spectroscopic determination.