Abstract— Fluorescence lifetimes, quantum yields and polarization spectra were measured for indole, 3-methylindole and 2,3-dimethylindole in non-polar solvents. The results indicate simultaneous emission from thermally equilibrated 1La and 1Lb levels, with 1La→1A dominating the 2,3-dimethylindole emission, and 1Lb→1A dominating the indole emission. These results are consistent with previous assignments of the 0-0 transitions in absorption for these compounds. Radiative rates are: 1La→1A, 2·0 × 108 S-1 and 1Lb→1A. 0·62 → 108 S-1. In addition, the temperature dependence of the excitation and emission spectra are presented, which show that aggregation occurs with these indoles in hydrocarbons below approximately - 110°C. Possible applications to tryptophyl emission in the hydrophobic interiors of proteins are briefly discussed.