Abstract: A system for mounting one article to another article incorporates a clamp having a base configured to interlock with a Picatinny-type rail. In one form, the clamp has a quick-connect device serving as a platform for quickly attaching different articles to the clamp, and in another form a coupler joins two clamps that are attachable to respective different rails. The clamp preferably is spring biased to one position and manually operated to a second position to facilitate application to and removal from the rail. The invention thus provides an easily customizable equipment rack that can be mounted to almost any surface, allowing it to be extremely versatile. For example, it could be used to mount a shelf to a wall surface, or for supporting tools, weapons, and other articles on various structures, or for mounting accessories to a weapon or to other objects.