Provided are curable compositions including a base part comprising an amine-reactive curable resin and a curative part comprising a polymeric toughener dissolved in an amine. The polymeric toughener, optionally a rubbery polymer or thermoplastic polymer, is solid at ambient conditions with a weight average molecular weight of at least 5,000 g/mol while the amine is a liquid at ambient conditions. The curable composition is cured by mixing the base and curative parts with each other. Hardened compositions obtained thereof can achieve increased toughener loading, resulting in high peel and shear strength performance over a wide range of temperatures, including at temperatures exceeding 180° F. (82° C.).