Described herein are the rotationally resolved one-photon fluorescence excitation spectra of several vibronic bands in the S1 ← S0 electronic transitions of three linear polyenes in the gas phase, 1,3,5,7-octatetraene (OT), 1,3,5,7-nonatetraene (NT), and 2,4,6,8-decatetraene (DT). Several of the spectra are significantly perturbed by an apparent centrifugal distortion in the S1 state of OT, owing to the high frequency of rotations parallel to a and the low frequency of an in-plane bending mode (ν48), by Coriolis coupling in the S1 state of NT, involving ν48 and a nearby methyl torsional level, and by torsion−rotation coupling in the S1 states of NT and DT, owing to a significant reduction in the excited-state torsional barrier(s) compared to the ground state. Nonetheless, the inertial parameters of eight different S0 and S1 vibronic levels have been determined, from which it is concluded that the carriers of the spectra are in all cases the trans,trans isomers. The important role of ν48 as a promoting mode for S1−S2 vibronic coupling, the source of the S1 ← S0 oscillator strength, is confirmed. Finally, the measured differences in the rotational constants of the S0 and S1 states (e.g., ΔA = 2532, ΔB = −11.7, and ΔC = −11.0 MHz for the vibronic origin of OT) provide new information about the changes in geometry that occur when the photon is absorbed.