We studied the interaction of lipid bilayers with short-chain alcohols, using molecular dynamics on different length scales. We used detailed atomistic modeling and modeling on a length scale on which an alcohol is just an amphiphilic dimer. Our strategy was to calibrate a coarse-grained model against the detailed model at selected state points at a low alcohol concentration and then perform a wider range of simulations with the coarse-grained model. We obtained semiquantitative agreement with experimental data for the major observables, such as the order parameter and area per molecule. We found a linear increase in the area per molecule with the alcohol concentration. The alcohol molecules in both system descriptions were in close contact with the glycerol backbone. Butanol molecules could enter the bilayer to some extent, in contrast to the behavior of shorter alcohols. At very high alcohol concentrations, we found clearly increased interdigitation between leaflets. (c) 2005 Wiley Periodicals, Inc.