Psychological inflexibility is a psychopathological process referring to the tendency for behavior to be overly controlled by internal experiences to an extent that interferes with quality of life. Some studies indicate that psychological inflexibility is linked to hoarding, but findings have been mixed. This inconsistency may be due to reliance on general measures of psychological inflexibility in prior research as there was previously no validated measure to assess psychological inflexibility as it relates to hoarding. The present study developed and validated a measure of hoarding-related psychological inflexibility, the Acceptance and Action Questionnaire for Hoarding (AAQH) in a college student sample with elevated hoarding symptoms (n = 201). The AAQH demonstrated a two-factor structure and good internal consistency, construct validity, and incremental validity over a general measure of psychological inflexibility, the AAQ-II. The potential research and clinical utility of the AAQH as well as limitations of this preliminary validation study are discussed.