We report ONIOM calculations using B3LYP/D95** and AMI on beta-sheet formation from acetyl(Ala)(N)NH2 (N = 28 or 40). The sheets contain from one to four beta-turns for N = 28 and up to six for N = 40. We have obtained four types of geometrically optimized structures. All contain only beta-turns. They differ from each other in the types of beta-turns formed. The unsolvated sheets containing two turns are most stable. Aqueous solvation (using the SM5.2 and CPCM methods) reduces the stabilities of the folded structures compared to the extended strands.