Proximity data consist of measures of similarity or dissimilarity between members of a set of stimuli, individuals or objects of interest, and occur in many different disciplines, particularly psychology, sociology, and market research. In some instances such data arise from calculations carried out on the usual multivariate data matrix, the elements of which record the values of a number of variables on a number of individuals. In other circumstances, proximity data are collected directly from experiments in which human subjects are asked to make judgements about the similarity or dissimilarity of pairs of stimuli. This text explores a variety of methods for analyzing proximity data, complete with numerous examples and background information.