Soybean straw and wheat straw show promise as annually renewable alternative to traditional wood sources for fiberboard. Epoxidized sucrose soyate has shown high performance as a thermosetting resin and could be adapted for use in fiberboard. This research evaluated the physical and mechanical properties of medium density fiberboard using wheat and soy straw while using various binders, including epoxidized sucrose soyate. Additionally, several experiments were conducted to evaluate optimal process conditions for hammer milling of soy and wheat straw to reduce fines and maximize viable fiber content for fiberboard manufacture. Test results indicate that soy straw boards were not able to meet the properties of wheat straw boards on all levels. Epoxidized sucrose soyate was not effective as the sole binder but had similar properties when blended with MDI resin. Optimal conditions were identified to reduce fines and maximize the viable fiber fraction produced for both wheat and soy straw.