The stability of two-parameter families of walking vector solitons of
coupled nonlinear Schrodinger equations in investigated. It is shown t
hat all known, lowest-order soliton types, namely, slow, fast, vector
in phase, and vector out of phase are dynamically stable in certain re
gions of the parameter space. The condition of linear marginal stabili
ty of the solitons is not necessarily given by an explicit geometric c
riterion, because soliton instability mediated by the existence of com
plex eigenvalues of the corresponding Lyapunov operator is found to oc
cur also. [S0031-9007(98)07659-5].