A study investigating the affect of formulating procedures on material properties was performed for model high-performance epoxy adhesives. Analyses were conducted on materials fabricated with 16 wt % butadiene-acrylonitrile reactive rubber, difunctional and tetrafunctional epoxies, bisphenol A : dicyandiamide, and diuron. Pre-reaction steps involving the reactive rubber, bisphenol A, and epoxies were varied so that different systems were obtained prior to and after cure. Lap shear and mode I and II fracture toughness tests showed that the formulating procedure significantly affected the performance properties. Differential scanning calorimetry revealed that the formulating procedure slightly affected the number of bonds formed during cure. Dynamic mechanical analysis suggested that increased flexibilized rubber in the continuous phase of the adhesives may lead to inferior bonding characteristics. This analysis also showed that the dispersed phase composition was largely unaffected by the formulating procedure and not dependent on the size or shape of the dispersed phase. Finally, optical microscopy showed that the formulating-mixing procedure had a strong influence on the size and shape of the dispersed phases. Overall, the results suggested that polymer mobilities and structure affected the morphology and adhesive ability and must be analyzed with fundamental processing-structure-property interrelationships.