Quantities of high-quality rubber gumstock, well below the permissible contaminant levels established by the Federal Emergency Management Agency (FEMA) and the American Society for Testing Materials (ASTM), have been prepared in the Food Protein Research and Development Center's Industrial Crops Solvent Extraction Pilot Plant using a batch-processing approach. The basic unit operations of this approach are compatible with the infrastructure of screw press cottonseed oil mill operations in the United States. Process limitations in shrub preparation, mixing, miscella filtration, and removal of solvent from the finished rubber were identified and subsequently minimized or resolved. Different combinations of solvents and alcohols for rubber precipitation, antioxidants, extraction temperatures, shrub sources, storage conditions, and preparation methods were investigated; and their effects on rubber material properties were evaluated. Compounding studies and physical testing have shown that the center's guayule rubber is comparable to both hevea rubber and Mexican guayule rubber prepared by an aqueous extraction method. These results confirm the overall adequacy of the process. However, a number of processing steps require initial evaluation or further “fine tuning” to ensure development of a fully optimized processing scheme.