People who hoard compulsively but do not have other symptoms of obsessive-compulsive disorder (OCD) differ in several respects from hoarders with OCD. Pertusa et al. (CME, p. 1289) found that those without OCD reported less hoarding-related checking and obsessions, cited intrinsic or sentimental value as motivation, and were older when their clutter was deemed excessive. Those with hoarding plus OCD scored higher on clinician ratings of severity and functional impairment. They were also more likely to hoard letters, receipts, old medication, and bizarre items, such as rotten food. On the other hand, both hoarding groups had more family history of OCD and hoarding than people with other anxiety disorders or community comparison groups. In an editorial on p. 1229, Drs. James Leckman and Michael Bloch examine hoarding as part of their developmental and evolutionary perspective on OCD.