The gas-phase resonance fluorescence spectra of 80Se2 excited by the argon ion laser lines at 4880 and 4765 Å consist of long series of Stokes and anti-Stokes R, P doublets. Measurements of these spectra combined with a detailed study of the absorption spectrum in this wavelength region show that the 4880 Å line excites R(38) in the 1–14 band, the 4765 Å line R(15) in the 0–12 band, both in the Ω= 1u–Ω= 1g component of the B3Σ–u–X3Σ–g transition. Improved vibrational and rotational constants for X1g(3Σ–g) are derived, as follows: G= 387.156 (v+½)–0.964 (v+½)2; F2: Bv= 0.090 16 – 2.98 × 10–4(v+½); F3: Bv= 0.090 22 – 3.01 × 10–4(v+½). The uncorrected relative intensities are in qualitative agreement with calculated Franck-Condon factors. In these series the qualitative variation of intensity with v″ is determined by the shape of the vibrational wavefunction in the upper state.