A closed fluid transfer system for fluidly interconnecting a syringe to any one of a patient I.V. set, a vial and an I.V. bag, the closed fluid transfer system comprising: a first adapter defining a first adapter lumen extending therethrough, the first adapter supporting a first adapter distal seal extending across a first end of the first adapter lumen and a first adapter luer connector at a second end of the first adapter lumen for selectively connecting the first adapter to the syringe, the first adapter supporting a first adapter proximal seal extending across the first adapter lumen at a location between the first adapter distal seal and the first adapter luer connector and spaced an axial distance from the first adapter distal seal the first adapter supporting a rear end of a needle within the first adapter lumen, wherein the first adapter distal seal is movable relative to a tip of the needle such that the tip of the needle penetrates through the first adapter distal seal, and wherein the first adapter distal seal is movable relative to the first adapter proximal seal to a second axial distance which is less than the first axial distance; and at least one second adapter (13, 15, 17) for fluidly interconnecting the first adapter to one of the patient I.V. set, the vial and the I.V. bag, the at least one second adapter defining a second adapter lumen extending therethrough, the at least one second adapter supporting a second adapter seal extending across a first end of the second adapter lumen and a connector at a second end of the second adapter lumen for selectively connecting the second adapter to one of the patient I.V. set, the vial and the I.V. bag; wherein when the at least one second adapter is coupled to the first adapter, the second adapter seal abuts the first adapter distal seal and moves the first adapter distal seal relative to the tip of the needle, and relative to the first adapter proximal seal, such that the tip of the needle penetrates through the abutting first adapter distal seal and second adapter seal, and such that the first adapter distal seal and the first adapter proximal seal are approximated. a first adapter defining a first adapter lumen extending therethrough, the first adapter supporting a first adapter distal seal extending across a first end of the first adapter lumen and a first adapter luer connector at a second end of the first adapter lumen for selectively connecting the first adapter to the syringe, the first adapter supporting a first adapter proximal seal extending across the first adapter lumen at a location between the first adapter distal seal and the first adapter luer connector and spaced an axial distance from the first adapter distal seal the first adapter supporting a rear end of a needle within the first adapter lumen, wherein the first adapter distal seal is movable relative to a tip of the needle such that the tip of the needle penetrates through the first adapter distal seal, and wherein the first adapter distal seal is movable relative to the first adapter proximal seal to a second axial distance which is less than the first axial distance; and at least one second adapter (13, 15, 17) for fluidly interconnecting the first adapter to one of the patient I.V. set, the vial and the I.V. bag, the at least one second adapter defining a second adapter lumen extending therethrough, the at least one second adapter supporting a second adapter seal extending across a first end of the second adapter lumen and a connector at a second end of the second adapter lumen for selectively connecting the second adapter to one of the patient I.V. set, the vial and the I.V. bag; wherein when the at least one second adapter is coupled to the first adapter, the second adapter seal abuts the first adapter distal seal and moves the first adapter distal seal relative to the tip of the needle, and relative to the first adapter proximal seal, such that the tip of the needle penetrates through the abutting first adapter distal seal and second adapter seal, and such that the first adapter distal seal and the first adapter proximal seal are approximated.