The force profile between a silicon nitride tip and solid substrates in short linear alcohols (CnH2n+2O, n =2−8) has been measured with an atomic force microscope. On a hydrophilic substrate like mica the profilewas oscillatory. The period was longer than the length of a single molecule and increased proportional to thechain length. This indicates that the molecules are in a roughly upright position and may form a double-layer.On a hydrophobic substrate the force profiles showed two distinct jumps that are independent of the chainlength of the alcohols, indicating that the molecules lie flat on a hydrophobic substrate.