The aggregation of poly(γ‐benzyl L‐glutamate) has been studied by measuring the specific Kerr constants (B/c) over a tenfold range of concentration and the intrinsic viscosities of solutions of a low molecular weight sample of the polymer in four solvent mixtures, viz., benzene–dimethylformamide (DMF), benzene–ethylene dichloride (EDC), dioxane–DMF and dixoane–EDC. Sharp changes are found in the experimentally determined quantities on the addition of small amounts of polar solvent to solutions of the polymer in either benzene or dioxane; this implies that lyotropic phase changes are occuring. The aggregation in benzene produces a birefringent, viscous solution which is probably a smeetic liquid crystal. This changes on addition of polar solvent to an aggregation involving only a few molecules; the second aggregate is most likely antiparallel. Aggregation in dioxane is antiparallel; the existence of a smectic phase is ruled out by the low intrinsic viscosities. Copyright © 1970 John Wiley & Sons, Inc.