Abstract: Curable compositions contain (i) a free radical polymerizable organosilicon monomer, oligomer or polymer; (ii) an organoborane amine complex; optionally (iii) an amine reactive compound having amine reactive groups; and optionally (iv) a component capable of generating a gas when mixed with a compound bearing active hydrogen and a catalyst. The curable compositions can be used as a rubber, tape, adhesive, foam, pressure sensitive adhesive, protective coating, thin film, thermoplastic monolithic molded part, thermosetting monolithic molded part, sealant, gasket, seal, or o-ring, die attachment adhesive, lid sealant, encapsulant, potting compound, or conformal coating. The compositions can also be used in composite articles of manufacture such as integrally bonded device including electrical and electronic connectors and scuba diving masks, in which substrates are coated or bonded together with the composition and cured.