A description is given of an analytical solution to the scattering Mueller matrix of an ensemble of small particles that may be of different shape, size, composition, and structure. It is derived within the framework of the generalized multiparticle Mie solution (GMM). Provided that all individual T matrices of a group of particles are known analytically or can be computed accurately, light scattering by an arbitrary configuration of these particles can be predicted precisely for both fixed and random orientations. In practical implementations, the applicability of the solution is limited by the size of individual particles only, and there is no restriction on the overall dimension of an ensemble. This multiparticle-scattering formulation of the GMM has been implemented in several public-domain computer codes. In practical calculations, the maximum total number of particles in an ensemble that can be handled depends on the largest size of the individual components and the availability of computer memory.