The role of internal excitation in affecting electron-molecule cross sections is analyzed fo H2, N2 and O2 systems. Particular emphasisi is given to the role of vibrational energy in affecting both the resonant and non-resonant electron molecule cross sections. In general for resonant transitions the cross sections dramatically depend on the nitial vibrational quantum number of the target, while a minor effect is found for direct (non-resonant) transtions. Cross sections in this last case reflect the form of Franck-Condon factors and Franck-Condon densities linking the relevant bound-bound or bound-continuum transitions. A similar behaviour is presented when the target is electronically excited. In this case, however, the enhancement of cross section is much higher.