The data acquired from most surface analysis instrumentation are composed of two parts, (a) peaks of interest, and (b) a background. The background is usually regarded as a hindrance to data processing and various techniques have been developed to eliminate or reduce its effects. These methods include linear and integral background subtraction, signal differentiation, dynamic background subtraction, special modulation techniques, and deconvolution. This paper will review methods for background subtraction in secondary ion mass spectroscopy, ion scattering spectroscopy, x-ray photoelectron spectroscopy, and Auger electron spectroscopy.