A bottle cap assembly (2) for use with a bottle (4) having a mouth (10) and a shoulder (18). The assembly comprises an inner cap piece (6) and a separate outer cap piece (8). The inner cap piece (6) fits over the mouth (10) of the bottle and the outer cap piece (8) surrounds the inner cap piece (6) and fits on the shoulder of the bottle (4). The inner cap piece (6) may have a circular top (26) and the outer cap piece (8) is preferably shaped to conform with the shape of the bottle (4). The outer cap piece (8) may snap fit onto a recess (16) on the bottle (4). The inner cap piece (6) has at least one hole permitting direct access to the interior of the bottle.