We study the sets of inertias achieved by Laplacian matrices of weighted signed graphs. First we characterize signed graphs with a unique Laplacian inertia. Then we show that there is a sufficiently small perturbation of the nonzero weights on the edges of any connected weighted signed graph so that all eigenvalues of its Laplacian matrix are simple. Next, we give upper bounds on the number of possible Laplacian inertias for signed graphs with a fixed flexibility τ (a combinatorial parameter of signed graphs), and show that these bounds are sharp for an infinite family of signed graphs. Finally, we provide upper bounds for the number of possible Laplacian inertias of signed graphs in terms of the number of vertices.The signs of the real parts of the eigenvalues of a coefficient matrix in a system of linear ordinary differential equations determine the stability of the dynamical system that it is describing. In this paper, we focus on systems with a coefficient matrix that is a symmetric Laplacian matrix, for which all eigenvalues are real. In order to understand the behaviour of such a dynamical system, the number of positive, negative, and zero eigenvalues of the coefficient matrix, together known as the inertia of the matrix, are studied. The sign pattern of the Laplacian matrix is described by a graph with positive and negative edges. The spectrum of the Laplacian of a signed graph reveals important information about the underlying dynamics, for example see [1,2,3].A signed graph is a simple graph G = (V (G), E(G)) together with an assignment of the signs + or − to its edges. An edge is positive if it is assigned the sign +, and negative if it is assigned the sign −. We assume throughout that a signed graph G has vertex set V (G) = {1, 2, . . . , n}, and a total of m edges of which m + are positive and m − are negative. The number of components of *