The presence of natural discontinuities in a rock mass is the main factor that distinguishes rock slope from soil slope analyses. One problem peculiar to rock mechanics is the choice of the most appropriate approach (continuous or discontinuous) to follow for taking the presence of the discontinuities into account when modelling the rock mass. Starting from these considerations, the present Chapter presents the differences between the continuous and discontinuous methods. For both types of methods a description of the input geometrical and mechanical parameters and the procedures to assess their values are provided. Then, in the case of the discontinuous approach the “routine” methodology for the assessment of the stability of rock slopes is given. Finally, two promising research fields are presented: the fracture mechanics based methodologies for the analysis of the progressive failure in rock slopes, and the stochastically-based approach for the modelling of the mechanical behavior of rock formations with a block-in-matrix arrangement. The main characteristics of these geotechnically complex rock units are also described.