Surfactants aggregate to form structures at molecular level. The questions that arise are what causes structures such as spheres, cylinders, lamellae, etc., to form, and when is one shape preferred over another. Both questions are very difficult to answer, but significant progress has been made. These have been reviewed, with emphasis on the contributions by this investigator. Further question to ask would be if the structures have any impact on mass transfer, and they do. Finally, the emerging areas in surfactant science and technology is briefly noted.