When does clutter turn into a compulsive hoarding disorder? In Stuff: Compulsive Hoarding and the Meaning of Things (Houghton Mifflin Harcourt, 2010), pioneering hoarding researchers Randy Frost and Gail Steketee describe various manifestations of what is now recognized as a mental disorder that afflicts six million Americans. Hoarding is much more than acquiring numerous possessions. Those with the disorder typically cannot stop acquiring stuff (which often includes things others recognize as useless or garbage) and ultimately fill up rooms, houses, even multiple living spaces to the point where they sever personal relationships and endanger their own health and safety. Fascinating and disturbing stuff.