The VUV-MATI spectrum of trans-1,3-butadiene (BD) has been recorded and analyzed. The lowest ionization potential is 73.143 cm(-1). The assigned vibrational bands agree well with previous measurements, and three new bands are assigned. Fragment PIRI experiments were carried out on the (A) over tilde((2)A(u)) <-- (X) over tilde(B-2(g)) transition in BD+, and the optical spectrum was analyzed. Information regarding the fragmentation mechanisms that characterize the observed optical spectrum is presented. At low PIRI-photon energies, the fragmentation process is a one photon process yielding primarily C3H3+. As the PIRI photon energy increases, more and more C4H4+ is produced, indicating that the two-photon process producing this fragment involves the (D) over tilde state.