This volume is a collection of papers by Robert Steinberg. It contains all of his published papers on group theory, including those on “special representations” (now called Steinberg representations), tensor products of representations, finite reflection groups, regular elements of algebraic groups, Galois cohomology, universal extensions, etc. At the end of the book, there is a section called “Comments on the Papers”. The comments by Steinberg explain how ideas and results have evolved and been used since they first appeared.