A card edge connector assembly for connecting a pair of electrical cards to a printed circuit board includes an upper connector and a lower connector. The upper connector includes a first insulative housing with a plurality of first terminals mounted therein. The first insulative housing defines a recess thereunder and extending from a first front face of the first insulative housing thereof. The lower connector includes a second insulative housing with a plurality of second terminals mounted therein and received in said recess under the upper connector. The second insulative housing defines a second front face which is in alignment with the first front face in a vertical direction.