Ab initio calculations at the Hartree-Fock (HF) and second-order Moller-Plesset (MP2) levels have been carried out on 1,3-cycloheptadiene in an attempt to resolve previously determined conflicting experimental and computational results. Inversion barriers from the C-s to the C-2 structures were calculated at these levels of theory utilizing the 6-31G** basis set. Transition states and minima were located at all levels of theory and, at the HF level, verified through vibrational frequency calculations. Additionally, point calculations at the MP3 level were performed on the MP2/6-31G** stationary points using the same basis set. The HF result shows the C-2 structure to be 2.5 kcal/mol above the C-s, while the MP2 calculation finds both conformers to be nearly energetically equal, with the C-2 lower in energy by 0.3 kcal/mol. The MP3/6-31G**//MP2/6-31G** results predict the C-s structure to be 0.8 kcal/mol lower in energy than the C-2 structure. The C-s structure at the MP2 level is in excellent agreement with the available microwave and electron diffraction data. The HF energetic results agree with the molecular mechanics calculations and seem to confirm the electron diffraction and microwave determination of a C-s structure, while the MP2 and MP3 energetic results allow for the possibility of the presence of a C-2 structure, as evidenced by NMR data.