In Part 1, it was demonstrated that intensity measurements on an actual beam in the laboratory allow one to determine so-called density matrices related to the beam shape coefficients encoding the beam and used in many expressions of the generalized Lorenz-Mie theory. In this paper, expressions in the generalized Lorenz-Mie theory are rewritten and it is shown that they can be expressed in terms of the density matrices rather than in terms of beam shape coefficients, leading to what is called the density matrix approach to the generalized Lorenz-Mie theory. The possibility of rewriting the generalized Lorenz-Mie theory in terms of quantities describing the illuminating beam and experimentally measurable in the laboratory offers new opportunities in optical characterization.