In this paper, several sources of uncertainty in electric power systems are incorporated into the dynamic stability analysis of the system. Operating point stability is considered, with the system model written in state variable notation. The sensitivites of the eigenvalues of the associate matrix are used to calculate the statistics of eigenvalue locations. When the uncertainties considered are approximated by the multivariate normal distribution, the probability of dynamic stability is computed using the generalized tetrachoric series. The principle advantages of this method over multiple runs of a deterministic stability study are rapid calculation times and the availability of consistently calculated probability of operating point stability figures.