The multilevel fast multipole algorithm (MLFMA) is applied to the analysis of plane-wave scattering from multiple conducting and/or dielectric targets, of arbitrary shape, situated in the presence of a dielectric half-space. The multiple-target scattering problem is solved in an iterative fashion. In particular, the fields exciting each target are represented as the incident fields plus the scattered fields from all other targets. The scattered fields from each target are updated iteratively, until the induced currents on all targets have converged. The model is validated with an independent scattering algorithm, and results are presented for several example multitarget scattering scenarios.