This book introduces and surveys bilinear control systems theory from a mathematical viewpoint. The exposition is at the first-year graduate level. Topics include an introduction to Lie algebras, matrix groups and semigroups; the controllability, stabilization, and observability of bilinear systems; nonlinear systems analytically equivalent to bilinear systems; series representations for input-outputmappings; and random inputs. To assist the reader there are exercises; Mathematica scripts; and appendices on matrix analysis, differentiable maps and manifolds, Lie algebra, and Lie groups.