Aqueous compositions can be thickened without increasing stringiness, by using polymers of polyacrylic acid, poly(2-acryamide-2-methylpropanesulfonate), or salts thereof, having a weight average molecular weights of 500,000 to 8,000,000 as thickeners. The polymers contain no more than 10 mass % of polymers having a molecular weight of 10,000,00 or more, and/or contain no more than 10 mass % of polymers having more than three times the weight average molecular weight. Aqueous solutions of these polymers exhibit a low degree of stringiness, and are particularly useful as thickeners for cosmetics.