The fluorescence and phosphorescence band positions of mono substituted benzenes are recorded at 77°K in four solvents, and the band maxima are correlated with substituent effects. No correlation of the fluorescence band maxima is obtained until the electron donating substituents are separated from the electron acceptors. The phosphorescence band maxima do not correlate well with Hammett sigma constants. With the exception of N, N-dimethylaniline, the fluorescence maxima are independent of the nature of the solvent. Both good electron donor and acceptor groups diminish the fluorescence and phosphorescence transition energies. With good electron donor and acceptor groups, there is a significant red shift in phosphorescence on going from nonpolar solvents to acetonitrile. The phosphorescence results are interpreted in terms of intramolecular charge transfer (ICT) and charge transfer to solvent (CTTS) processes in competition with one another.