Green weight and green weight per unit volume relationships for loblolly pine trees have not been studied extensively and models for predicting weights across broad geographic areas are not readily available. In this regard three basic interrelated issues were addressed in this study: 1) an examination of weight per unit volume relationships, 2) an assessment of how tree, stand, and geographic characteristics affect weight per unit volume relationships, 3) a derivation of models of weight per unit volume for predicting total bole weight and merchantable weight, 4) a derivation of models for predicting green weight directly, and 5) a comparison of objectives 3) and 4). This study showed that green weight per unit volume varies somewhat within stems, but the variation is large. There is no discernable trend by stand characteristics, and the geographic trends were inconclusive. Data from four data sets were combined and region-wide prediction models for total green weight, green weight to any upper merchantable diameter, and green weight to any upper merchantable height were developed for loblolly pine trees. / Master of Science