A multi-fiber fiber optic receptacle and plug assembly, comprising: a fiber optic receptacle defining a first alignment and keying feature, the receptacle comprising: a receptacle housing defining an internal cavity; a ferrule retainer secured to the receptacle housing; a receptacle ferrule at least partially disposed within the internal cavity of the receptacle housing and at least partially disposed within the ferrule retainer; a biasing spring for biasing the receptacle ferrule in the direction of the receptacle housing; and a fiber optic plug adapted to be mated with the receptacle and defining a complimentary second alignment and keying feature, the plug comprising; a plug outer housing defining a passageway; a plug sub-assembly disposed within the passageway and comprising an inner housing, a plug ferrule and a biasing spring, the plug ferrule a least partially disposed within the inner housing; and an alignment sleeve disposed adjacent a forward end of the inner housing, the plug ferrule at least partially disposed within the alignment sleeve, wherein the alignment sleeve is retained and positioned with the plug outer housing such that a key slot of the alignment sleeve is aligned with a key slot defined by the plug outer housing; and wherein the second alignment and keying feature of the plug operatively engages the first alignment and keying feature of the receptacle when the plug is inserted into the receptacle to properly align the receptacle ferrule and the plug ferrule in opposing relation. a fiber optic receptacle defining a first alignment and keying feature, the receptacle comprising: a receptacle housing defining an internal cavity; a ferrule retainer secured to the receptacle housing; a receptacle ferrule at least partially disposed within the internal cavity of the receptacle housing and at least partially disposed within the ferrule retainer; a biasing spring for biasing the receptacle ferrule in the direction of the receptacle housing; and a receptacle housing defining an internal cavity; a ferrule retainer secured to the receptacle housing; a receptacle ferrule at least partially disposed within the internal cavity of the receptacle housing and at least partially disposed within the ferrule retainer; a biasing spring for biasing the receptacle ferrule in the direction of the receptacle housing; and a fiber optic plug adapted to be mated with the receptacle and defining a complimentary second alignment and keying feature, the plug comprising; a plug outer housing defining a passageway; a plug sub-assembly disposed within the passageway and comprising an inner housing, a plug ferrule and a biasing spring, the plug ferrule a least partially disposed within the inner housing; and an alignment sleeve disposed adjacent a forward end of the inner housing, the plug ferrule at least partially disposed within the alignment sleeve, wherein the alignment sleeve is retained and positioned with the plug outer housing such that a key slot of the alignment sleeve is aligned with a key slot defined by the plug outer housing; and a plug outer housing defining a passageway; a plug sub-assembly disposed within the passageway and comprising an inner housing, a plug ferrule and a biasing spring, the plug ferrule a least partially disposed within the inner housing; and an alignment sleeve disposed adjacent a forward end of the inner housing, the plug ferrule at least partially disposed within the alignment sleeve, wherein the alignment sleeve is retained and positioned with the plug outer housing such that a key slot of the alignment sleeve is aligned with a key slot defined by the plug outer housing; and wherein the second alignment and keying feature of the plug operatively engages the first alignment and keying feature of the receptacle when the plug is inserted into the receptacle to properly align the receptacle ferrule and the plug ferrule in opposing relation.