A composite fabrication vent assembly for connection to an inflatable bladder, the combination of a vent assembly and an inflatable bladder, and a method of mechanically connecting a vent assembly and a bladder. The vent assembly comprises a body member having a first clamping surface, a clamping member having a second clamping surface, and a carriage member interconnecting the body member and the clamping member, with the first and second clamping surfaces in opposing relationship. With the open end of an inflatable bladder inserted between the opposed clamping surfaces, the carriage member is adapted to translate the body member and clamping member toward one another to form an airtight seal with the inflatable bladder. A controlled source of pressurized gas, connected to a gas inlet of the vent assembly, can then inflate and deflate the bladder in a controlled manner through one or more passageways in the vent assembly.