The role of representation theory in algebra is an important one and in this book Manz and Wolf concentrate on that part of the theory that relates to solvable groups. In particular, modules over finite fields are studied, but also some applications to ordinary and Brauer characters of solvable groups are given. The authors include a proof of Brauer's height-zero conjecture and a new proof of Huppert's classification of 2-transitive solvable permutation groups.