Abstract: An improved data processing system and operating system having a selectable scheduler. An operating system kernel is provided having a standardized interface for permitting the installation of a selected one of multiple diverse schedulers for use in different environments. System resources which may include memory, input/output devices and file systems are thereafter optimally allocated for a selected set of applications and a particular environment within the data processing system by permitting a user to install a selected one of the multiple schedulers which directly controls allocation of processor time, thereby indirectly allocating system resources. The standardized interface within the operating system kernel is preferably provided utilizing a kernel extension mechanism and installation of a selected one of the multiple schedulers may occur automatically, in response to system initialization, or may be selectively achieved during operation of the data processing system.