We report fluorescence imaging of single dye molecules on a glass substrate by two-photon excitation with femtosecond pulses from a mode-locked Ti:sapphire laser. The single-molecule images exhibit a high signal to background ratio (>30:1) and a high spatial resolution (fwhm < lambda/3). A quadratic intensity dependence of single-molecule emission rate is experimentally verified, and single-molecule emission spectra are recorded with two-photon excitation. A comparison of photobleaching rates is made between one-photon and two-photon excitation schemes.