Guidance and control system design for hypersonic vehicles is more challenging than their subsonic and supersonic counterparts. Some of these challenges are (i) coupling between the aerodynamic, structural and propulsion sub-systems (ii) uncertainty involved in modeling these couplings and (iii) state-space constraints. Proposed research seeks to address these challenges using advanced robust control system design techniques. Key components of the proposed research are (i) hypersonic vehicle modeling, (ii) uncertainty representation, (iii) robust controller designs, and, (iv) robustness evaluation tools. Personnel at OSI have extensive experience in the area of flight control system design and flight vehicle modeling. Phase I research will demonstrate the feasibility by using existing longitudinal hypersonic vehicle models. Phase II research will pursue three dimensional modeling of the hypersonic vehicle alongside advancing the control system design. A complete version of the control system design software will be developed and provided to NASA by the end of Phase II work.