Abstract INTRODUCTION THE diallel cross has become a common method of analyzing intra-specific genetic variability among crosses (partial diallel) or among parental subpopulations and their crosses (full diallel). The breeder needs the full diallel to determine whether crossing per se is of value in improving productivity. He needs further to determine the relative importance of certain kinds of specific combining ability, to indicate whether extensive crossing is needed to exploit nonadditive genetic variation. A diallel analysis that allows estimation of maternal effects is needed to determine whether reciprocal crosses are likely to be equivalent. This study estimates the relative importance of general and specific combining ability and maternal influence in strain and breed crosses for certain economic traits in pullets. MATERIALS AND METHODS Experimental Stock. Samples of three White Leghorn (W.L.) and three Rhode Island Red (R.I.R.) “closed-flock” strains were obtained from leading commercial breeders in 1956 and crossed in all…