A combination of an ab initio harmonic force field and experimentally determined frequencies is used to study the nascent energy distribution of naphthalene when photoexcited from the ground electronic state (S-0) to the first excited electronic state (S-1). We find extensive cooling of the nascent vibrational energy distribution for photoexcitation frequencies which are within 500 cm(-1) to the blue and to the red of the transition frequency omega(00) from the ground vibrational state of S-0 to the ground vibrational state of S-1. The experimentally measured pressure dependence of the internal conversion rates of naphthalene in the presence of argon gas are examined theoretically with an improved version of the Gaussian binary collision theory of Talkner, Berezhkovskii, and Pollak. We find, in agreement with experiment, that at low excitation energies, the lifetime of the excited state decreases with increasing pressure-a signature of vibrational cooling, while for high photoexcitation energies the lifetime increases, a signature of vibrational heating of the nascent distribution. The energy transfer per collision is found to be 25% of the excess (thermal) energy.