Phylogenetic comparative biology involves using an estimated phylogenetic tree (or set of trees) to make secondary inferences about trait evolution, diversification dynamics, biogeography, community ecology, and a wide range of other phenomena or processes. Phylogenetic comparative methods now feature in a vast array of disciplines, ranging from conservation biology, to virology, to sociolinguistics, to infectious disease epidemiology (and beyond). Over the past ten years or so, my phytools R package (Revell, 2012) has grown to become an important research tool for phylogenetic comparative analysis. phytools is a diverse contributed R library now consisting of hundreds of different functions covering a broad variety of methods and purposes in phylogenetic biology. In my seminar, I'll describe some significant features of and recent updates to phytools, while also illustrating several popular workflows of the phytools software.