In transonic flow, the aerodynamic interference that occurs on a strut-braced wing airplane, pylons, and other applications is significant. The purpose of this work is to provide relationships to estimate the interference drag of wing-strut, wing-pylon, and wing-body ar- his office, leaving with more answers than questions. I also appreciate the fact that he has always had a friendly attitude towards me. I have enjoyed interacting with Dr. Kapania, whose cheerful attitude and perpective on life and research is very similar to mine. I would like to acknowledge the contribution of Dr. Grossman to the team in the field of numerical calculations and his desire of improving the life of the graduate students by forming the Graduate Advisory Committee. Dr. Raj deserves a lot of thanks for providing me with useful advice throughout this project despite his busy schedule. I appreciate the fact that he has always been interested in knowing more about the evolution of my research work and career. The "virtual" presence of Dr. Haftka during our weekly meetings has been very beneficial because of his ability to foresee difficulties and to get the team members to not lose sight of the big picture.