Four studies examined a new measure of compulsive hoarding (Saving Inventory-Revised; SI-R). Factor analysis using 139 hoarding participants identified 3 factors: difficulty discarding, excessive clutter, and excessive acquisition. Additional studies were conducted with hoarding participants, OCD participants without hoarding, community controls and an elderly sample exhibiting a range of hoarding behavior. Internal consistencies and test-retest reliabilities were good. The SI-R distinguished hoarding participants from all other non-hoarding comparison groups. The SI-R showed strong correlations with other indices and methods of measuring hoarding (beliefs, activity dysfunction from clutter, observer ratings of clutter in the home) and relatively weaker correlations with non-hoarding measures (positive and negative affect and OCD symptoms). The SI-R appears to be an appropriate instrument for assessing symptoms of compulsive hoarding in clinical and non-clinical samples.