Free energy surfaces, or potentials of mean force, for the alpha- to 3(10)-helical conformational transition in polypeptides have been calculated in several solvents of different dielectric. The alpha- to 3(10)-helical transition has been suggested as potentially important in various biological processes, including protein folding, formation of voltage-gated ion channels, kinetics of substrate binding in proteins, and signal transduction mechanisms. This study investigates the thermodynamics of the alpha- to 3(10)-helical transition of a model peptide, the capped decamer of alpha-methylalanine, in order to assess the plausibility of this transition in the mechanisms of such biological processes. The free energy surfaces indicate that in each environment studied the alpha-helical conformation is the more stable of the two for the decapeptide, The thermodynamic data suggest that the alpha-helix is energetically stabilized and the 3(10)-helix is entropically favored.