The C (2) Pi(u)<--X( )2 Pi(g) electronic transition of C-4(-) has been studied by both one-color and two-color resonant two-photon detachment (R2PD) spectroscopy. The one-color spectrum reveals vibrational structure in the excited anion state. Transitions due to excitations in one of the symmetric stretching modes as well as the bending modes are observed. Spectral resolution in the one-color experiment is limited by power broadening; using two-color R2PD, rotationally resolved spectra of the origin and 2(0)(1) bands of the C (2) Pi(u)<--X (2) Pi(g) transition are obtained. Molecular constants determined by fitting the rotationally resolved spectra are generally in good agreement with a recent ab initio calculation by Schmatz and Botschwina [Int. J. Mass. Spec. Ion. Proc. 149, 621 (1995)]. Perturbations in the 2(0)(1) band are attributed to Fermi resonance interactions in the C (2) Pi(u) state.