Various forms of diallel crosses play an important role in evaluating the breeding potential of genetic material in plant and animal breeding (e.g., Hinkelmann, 1975, inA Survey of Statistical Design and Linear Models, 243-269. Amsterdam: North Holland). In this paper we consider the use of partial diallel crosses in incomplete block designs as environment designs. We discuss in detail a particular method of constructing such combined mating-environment designs by relating both component designs to certain types of partially balanced incomplete block designs. This method is compared with a generally applicable method of embedding partial diallel crosses in existing incomplete block designs as environment designs.