Two recent studies provide alternative views of the current state and future prospects of southern forests and timber supply: the Southern Forest Resource Assessment (SOFRA) and the Fifth Resources Planning Act Timber Assessment (RPA). Using apparently comparable data but different models and methods, the studies portray futures that in some aspects are quite similar and in others markedly different. This article focuses on what the differences and commonalities between the reports suggest about the key factors that help shape our views of the future of southern timber supply. What inputs and assumptions make important differences in projections of the South's timber supply future? We find that there are five major areas to watch: (i) gross land area ships from forest to urban and from agriculture to forest (not just net timberland area change); (ii) the sensitivity of pine plantation investments to expected timber prices; (iii) the responsiveness of southern timber demand to prices; (iv) age or date of the starting inventory and the definition of timber harvest (what products are included); and (iv) the basic yield assumptions and the timing of the yield impacts from improved management and timberland area change.