Second generation, or toughened, epoxy resin systems are under consideration for use on a large composite primary structural part such as a wing. A method of evaluating the properties of these materials, while at the same time considering design, structural and manufacturing requirements has been developed. Processability requirements for toughened epoxy resin systems have been established. Cost efficient manufacturing methods, such as pultrusion, have been investigated and found to be a feasible production method for composite structure. The use of pultrusion as a fabrication method for partially staged parts to be co-cured at a later date is being evaluated.