At StanCon 2018 I will present my new R package for ideal-point modeling with the Stan Markov Chain Monte Carlo sampler for Bayesian inference. This package allows for clustering of data around polarized axes to understand how and why people polarize themselves, whether in terms of political opinions or market products. I illustrate the package with applications drawn from the U.S. Senate and from Amazon product reviews of coffee products. I show how ideal point models can help us understand who the most polarized Senators and coffee products are, and also how the Bayesian version of the model adds powerful new features, including censoring for missing data.