The book describes the research work done by author during his PhD. It is suitable as reference book in the advance course of real-time system as well as for the researchers in the same field. It discusses the scheduling problem for real-time operating systems. Dynamic scheduling algorithms can not perform well during overloaded condition. The objective of the book is to get optimum performance in underloaded condition and to improve the performance of real-time systems in overloaded conditions. Initially, new algorithms are proposed with modifications in the conventional EDF algorithm. Then, ACO based dynamic scheduling algorithm for real-time operating systems has been proposed.An adaptive scheduling algorithm is also proposed as pure ACO based algorithm takes more time for execution. All algorithms are tested on single processor system, tightly coupled multiprocessor system and loosely coupled multiprocessor real-time systems. The book covers an important application of ACO in real-time scheduling.