We recently reported that beta-peptides can form discrete hetero-oligomers in aqueous solution. Here we describe the structure of such an oligomer as determined by X-ray crystallography. The structure of Zwit-1F reveals a homo-octamer of two cupped "hands" composed of both parallel and antiparallel 3(14)-helices. The core of the assembly is composed entirely of solvent-excluded beta(3)-homoleucine residues. The Zwit-1F assembly shares many of the physical characteristics of natural proteins.