Abstract: The invention relates to an adjustable helmet having a front shell and a back shell that are movably secured to one another and that comprise engaging members that may be held together by a locking mechanism comprising a cam that pivots about an axis extending in a direction that is substantially parallel to a side portion of the helmet. The locking mechanism of the present invention has the advantage of exerting a compressive force on a substantial portion of the engaging members thereby providing a more solid engagement. The locking mechanism also has the advantage of being easily replaceable by a conventional mounting screw assembly. The helmet of the present invention is particularly well suited for use in hockey or other like sports.