A nursing bottle includes a container having a threaded neck, a flanged nipple seated on the neck and a cap having a central opening through which the nipple extends. A threaded ring on the cap engages the threaded bottle neck with the outer circumferential edge of the nipple's flange compressed between the annular top and the rim of the bottle neck. A small slit in an area of thinned material at the nipple tip opens when the baby nurses and substantially closes when the baby is not nursing. The nipple flange includes a vent hole between its inner and outer circumferential edges, and an annular bead between its inner circumferential edge and the aperture. The annular bead engages the cap top when air pressure within the container is not substantially lower than air pressure external to the container, thereby providing a seal between the aperture and external air.
