Fluorescence up-conversion gating experiments with resolution of similar to150 fs have compared the fluorescence anisotropy relaxation time profiles for coumarins (C's) 151, 152A, and 153 in different solvents. The selective occurrence of longer anisotropy relaxation times for C151 in the presence of long-chain normal alcohols provides evidence for a strong hydrogen-bonded interaction in fluid solution specifically involving the NH2 group of C151. Experiments on coumarins in butanol/hexane binary solvents lead to similar conclusions, because C151 solutions show significantly longer anisotropy relaxation times than solutions of either C152A or C153. These results are consistent with measurements on jet-cooled molecular clusters, which showed that larger hydrogen-bonded aggregates selectively attach to the NH2 group of C151 via an N-(HO)-O-... type of hydrogen bond.