Landslides have been a perpetual menace for the hilly terrains of the Himachal Himalayas of India. Along the strategic National Highway 05, several incidents of rock slope failures have occurred in the past which have caused tremendous damage to the roads and other infrastructures, apart from claiming the lives of people. This study aims to assess the instability condition of one such unstable jointed rock slope in that area. The modes of failure have been first predicted using kinematic analysis of the slope. Then, distinct element method was applied using the Universal Distinct Element Code (UDEC) program to model the slope and determine the most vulnerable zones in the slope with the maximum probability of failure. The slope has been revealed to be unstable with a factor of safety less than 0.03 and maximum displacement of 6.51 cm at 100,000 calculation cycles. Both the planar sliding and direct toppling modes of failure predicted in the kinematic analysis have been validated using distinct element modeling with the help of three monitoring stations set up in the UDEC model. A displacement history chart has been constructed to compare the displacements of the three monitoring points in the slope model. The zone revealing toppling failure has shown the maximum horizontal displacement, whereas the zone revealing planar sliding has shown the maximum vertical displacement.