Infrared spectroscopy has a variety of uses in the paper industry, including competitive analysis, quantification of individual components, and identification of contaminants in both the manufacturing process and the product. This chapter reviews instrumentation and techniques that can be used to study paper or paper-related samples. It addresses data interpretation and some paper-related FT-IR applications. When selecting an instrument for testing or purchase the user should consider function, simplicity, reliability, and availability. There is a wide variety of sampling equipment offered for use in commercial FT-IR spectrometers. Neat film sampling is generally a quick and effective way to obtain spectra of liquid samples or extractions of solid samples. There are two sample-related problems which may arise with liquid samples. First, the sample may be too concentrated or too strong an absorber. Second, the sample may be too dilute or too weak an absorber.