Abstract: Over the past six decades, various models and versions of computer operating systems have been developed. These have been due primarily to the need of meeting both system and user expectations. The developments of different architectural frameworks in the design of operating systems have been a valuable tool in the attainment of these expectations. The usability, efficiency, portability and extensibility, to mention but a few are some goals which the monolithic, layered and microkernel structures try to address. Operating systems such as Window XP, UNIX and LINUS are designed based on the principles of the operating system architectures. This article gives an insight into the attainment of the operating system goals through various architectural models.