Moisture-curable, urethane-containing prepolymers containing urethanes incorporated into the prepolymer backbone and compositions thereof for use in sealant applications are disclosed. The prepolymers can be prepared by reacting an isocyanate-terminated urethane-containing adduct with a compound comprising a group reactive with an isocyanate group and at least one polyalkoxysilyl group. Compositions containing a moisture-curable, urethane-containing prepolymer and a moisture cure catalyst can be used to provide cured compositions exhibiting improved tensile strength. Compositions containing the prepolymers are useful in aerospace sealant applications.