We have investigated intermolecular electron transfer (ET) from electron-donating solvents (aniline and N,N-dimethylaniline) to coumarins in the excited state by means of the femtosecond fluorescence up-conversion technique. The coumarins we studied have a variety of structures with different substituents in the 4- and 7-positions. The ET occurs on a time scale ranging from a few nanoseconds to a couple of hundred femtoseconds depending on the structure of the coumarins and solvent. As for the 7-position, as the length of the alkyl chain on the amino group is longer, the ET is slower, and when the amino group is fixed by a double-hexagonal ring, it is slowest. When the electron-accepting ability of the substituent in the 4-position is increased, the reaction occurs faster. The origin of this substituent effect is mainly attributed to the variation of the energy gap between the reactant and product states. This is confirmed by theoretical calculations in terms of the extended Sumi-Marcus two-dimensional model. Good agreement between the experiment and calculation indicates that some of the reactions take place from the relaxed vibrational state of reactant to the excited vibrational states of high-frequency modes of product states. The simulated population decays for nonequilibrium configuration of solvents agreed well with experimental data. In the steady-state fluorescence spectra was also observed an effect of very fast fluorescence quenching due to ET; i.e., the amount of fluorescence Stokes shift depends on the rate of ET because the excited state is quenched in competition with thermal equilibration of the solvent configuration. We regard this spectral shift as the result of the "chemical timing" effect in solution.