Demand side management (DSM) is becoming a widely considered option to enhance the operational flexibility of power systems with penetration of renewable energy resources (RES). The implementation of DSM however, could endanger power system stability as it changes the amount, type and characteristic of system demand at the transmission level. The impact of various levels of DSM on power system angular stability has been studied in this paper. The impact of uncertainties associated with RES, system loading and fault location and duration have all been considered. The results show that depending on the level of application, the DSM could either improve or reduce small and large disturbance stability of the network and that while improving one, it may deteriorate the other. All simulations are carried out in DIgSILENT/PowerFactory environment using a modified version of the 68 bus NETS-NYPS test system.