Mixed clusters of Lennard-Jones atoms have been studied using molecular dynamic simulations. For sufficiently high impurity-host interaction energy, the structure is significantly distorted from those found for pure clusters, and the three-dimensional solid-liquid-like transition identified in pure system simulations is absent. Instead, at very low temperatures, structures may be characterized as having two-dimensional solid-like solvation shells formed by the host atoms surrounding the impurity. When these solvation shells are incomplete, well-defined two-dimensional solid-liquid transitions corresponding to the appearance of disorder in the solvation shells (two-dimensional melting) are observed as the temperature is increased. Studies of A13B13-type clusters are also reported. For the parameters studied, a clear segregation of species within the cluster is observed. © 1989.