Relationships between pre-breeding (March) and post-breeding (December) populations, and certain characteristics of reproductive effort are described for a population of bobwhites (Colinus virginianus) in western Tennessee. Numbers of quail on the 2100-acre study area ranged from 681 to 1269 in March, and from 1007 to 1587 in December during the period December. 1966 to March, 1974. A total of 1571 nests were studied to determine such items as hatching rate of nests with eggs (23.0%) and clutch size (x = 11.9 eggs). Of all variables examined, total number of nests found on the nesting area showed the strongest positive correlation with post-breeding population size (r=0.81) and summer gain (r=0.72). The predictive value of "total nests" for post-breeding populations was high (R22=0.65). Environmental events which influence the physiological condition and numbers in the breeding population are believed to be most important in determining summer gains and post-breeding (December) population density.