Optically active poly(beta -peptides) with proteinogenic side chains were synthesized via the polymerization of beta -amino acid-N-carboxyanhydrides (beta -NCAs) initiated using either NaOtBu or a nickel amido amidate complex. Although most of these low molecular weight poly(beta -peptides) have poor solubility in common organic solvents, those that were soluble were found to adopt stable chiral conformations in solution. Poly(N-xi-carbobenzyloxy-beta -L-homolysine) (2f) was observed to adopt a helical conformation in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), which could be disrupted by addition of methanesulfonic acid (MSA), a strong denaturing agent. The side-chain deprotected polymers, poly(beta -L-homolysine) (3) and poly(beta -L-homoglutamate) (4), were found to display pH-dependent conformation transitions in aqueous solution.