HREE live poultry viruses-fowl pox, Rous sarcoma and Newcastle diseasehave been employed experimentally at the Agricultural Research Center, Beltsville, Maryland, iin studies designed to test their action on parthenogenesis in eggs of Beltsville Small White (BSW) turkeys. Each of the viruses was found to have an enhancing influence on cells of parthenogenetic origin (OLSEN 1956, 1961; OLSEN and POOLE 1962 and unpublished observations). The same viruses, however, on being inactivated with beta-propnolactone and subsequently used to inoculate virgin BSW turkeys, had no affect on the level of macroscopic observable parthenogenesis in unfertilized eggs ( OLSEN 1962). Selective breeding has likewise been shown to be an effective method of increasing the predisposition for parthenogenesis in BSW turkeys. Between 1952 and 1963, the average level of parthenogenesis in turkey eggs at this station increased from 16.7% to over 40%. The most significant increase came in numbers of embryos, from a level of 0.2% in 1952 to about 12% in 1963 (OLSEN 1965). All turkeys were routinely vaccinated each year for fowl pox on reaching 6 to 8 weeks of age and again at 30 t o 32 weeks. The relative importance of roles played by genetic factors and fowl pox virus, especially in embryo production and hatched parthenogens, remains obscure. It was most aesirable, therefore, that a series of breeding tests be initiated whereby two genetically similar populations of turkeys would be selected for a high and/or low incidence of parthenogenesis, one group of birds in the presence of fowl pox virus, the other in the presumed absence of this virus. A cooperative study dlesigned to obtain information on the respective roles of genetic factors and fowl pox virus in parthenogenesis was initiated in 1961 with Pennsylvania State University, University Park, Pennsylvania.