An optically clear blend of (1) a water-soluble polymer of a vinyl lactam having the structure ##STR1## in which X represents an alkylene bridge having three to five carbon atoms or a copolymer thereof with 1 to 80 mole percent of a copolymerizable monomer containing a polymerizable ethylenic unsaturation; and (2) a tacky water-insoluble copolymer of (A) an ester or a mixture of esters having the structure ##STR2## in which R' represents hydrogen or methyl and R.sub.1 represents alkyl having from 1 to 14 carbon atoms and (B) from 1 to 12% by weight, based on the copolymer, of an ethylenic monomer containing an acid group, the vinyl lactam polymer or copolymer being present in an amount from 1 to 30% by weight of the blend and having a glass transition temperature from 20.degree. to 150.degree. C., and the tacky copolymer having a glass transition temperature below 0.degree. C. and being present in an amount from 70 to 99% by weight of the blend and having a viscosity less than 50,000 cp at 350.degree. F. The blend is useful as a pressure-sensitive adhesive composition.