A new self-consistent large-signal model for traveling-wave electroabsorption modulators (TW EAMs) is presented. A time-domain finite-difference approach is exploited to carry out a fully coupled analysis of the nonlinear distributed interaction between the microwave and optical fields in the device. RF and optical nonlinearities and saturation effects are taken into account, as well as the influence on the microwave electrode propagation parameters of the nonuniform distribution of the optical power along the traveling direction. The model is applied to the analysis of a InGaAsP/InP TW EAM in small- and large-signal operation. Its performance in terms of bandwidth, linearity, and chirp are investigated as examples of application. The technique is validated in small-signal low optical-power condition through a comparison with the results of a small-signal frequency-domain approach.