Data from plots established in unthinned loblolly pine plantations on cutover site-prepared lands were used to develop size class distribution and yield predictions. The data come from plantations of loblolly pine established over much of its natural range and represent a wide variety of stand conditions and site-preparation treatments. A three parameter Weibull density function was used to model diameter distributions, and a computer program, COYIELD, was developed to predict yields from stand attributes. The predicted yields should satisfactorily represent many sites in the Piedmont and Coastal Plain regions of the Southern United States.