Recent results from our laboratories show that the effects due to alcohols on two very different systems and processes, the thermal denaturation of transfer ribonucleic acid molecules and the micellization of several surfactant molecules, are strikingly similar and are closely paralleled in simpler physico-chemical properties of alcohol-water mixtures themselves. Accordingly, these results support the hypothesis that the dominant mechanism by which an alcohol affects these processes is through its effect on the structure of water. The main results of these investigations are reviewed and discussed in this paper.