This paper adopts a methodology to assess and rank the severity of the most frequent disturbances, 3 types in particular, that occur in the Mexican Interconnected System (MIS) when wind power plants (WPPs) are integrated. This is done by combining three stability indices from which an overall performance measure can be derived. In this way, it is possible to assess the severity of the disturbances such as generation tripping, line tripping and disconnection of loads. The indices under consideration include measures such as maximum amplitude, speed variation, and the Lyapunov exponent. For ranking the severity, a general index value is used. To confirm the effectiveness and performance of the proposed methodology, this paper investigates the 190-bus and 46-generator MIS equipped with an 8% of wind generation to quantitatively evaluate the severity of disturbances, resulting in 66% of unstable disturbances which are associated with the disconnection of loads.