Abstract Quadratic response theory for singlet and triplet operators (O. Vahtras et al., J. Chem. Phys., 97 (1992) 9178) have recently been applied to series of small molecules as well as to several aromatic compounds. A comparative analysis of results of such calculations on the phosphorescence effect in benzene, naphthalene and various azabenzenes and azanaphthalenes is presented. The information gained from such calculations concern polarization directions, oscillator strengths, radiative lifetimes and excitation energies for the triplet states. These quantities either refer to values averaged over the triplet states or to the specific triplet state spin sublevels. The vibronically induced phosphorescence problem, with specific reference to benzene phosphorescence which is forbidden both by spin and orbital symmetry and only allowed through the coupling of nuclear and electronic motions is also discussed. Results are compared with vapor phase data concerning total radiative lifetimes, and with data from phosphorescence microwave double resonance (PMDR) measurements of matrix isolated samples concerning the spin sublevel rates.