The invention provides amphiphilic compounds with hydrophobic and hydrophilic faces. The compounds can be readily prepared from steroids such as cholic acid or deoxycholic acid, which provide hydrophobic skeletons with structures similar to that of the lipid cholesterol. The compounds of the invention can be used to aid the solubilization, isolation, purification, stabilization, crystallization, and/or structural determination of membrane proteins, and to prepare micelles for delivery of a bioactive agent, such as a drug or a gene, to a subject.