Accurate spot detection and quantification is a challenging task that must be performed effectively in order to properly extract the proteomic information from two-dimensional (2-D) gel electrophoresis images. In Morris et al., Bioinformatics 24:529-536, 2008, we introduced Pinnacle, an automatic, fast, effective noncommercial package for spot detection and quantification for 2-D gel images, and subsequently we have developed a freely available gui-based interface for applying the method to a set of gels. In this chapter, we overview Pinnacle, and in a step-by-step manner we describe how to use the software to obtain spot lists and quantifications, to be used for comparative proteomic analysis.