A microcomputer program has been developed to be used as a teaching tool in quantitative genetics classes and as a means of analyzing real data from diallel crosses. The first part of the program, the simulation module, is of use as a teaching tool, offering students the opportunity to examine the ramifications of the underlying genetic and statistical assumptions of diallel mating designs. In particular, the program illustrates the difficulty in obtaining reliable estimates of genetic components of variance when employing a restricted number of parents. Using user‐entered values for the population mean, the number of parents, and genetic, environmental, and error variances, the program generates and analyzes multiple sets of data. The user can experiment by altering the parameters to test different strategies to cope with the difficulties inherent in the diallel mating design. The second module allows the analysis of real‐world experiments made in any of four diallel mating designs. The user may enter and correct data in the program itself, or import data as ASCII files from other programs. The program prints an analysis of variance table, and tables of means by variety and cross, heterosis, general and specific combining abilities, and genetic components of variance and their standard errors.