Methodology: The primary objective is to evaluate whether CREST significantly reduces hoarding symptoms and improves functional capacity and quality of life when compared to exposure therapy alone. The investigators will also examine the impact of treatment mediators; treatment adherence, changes in executive functioning, avoidance, symptom severity on outcomes. Age and executive functioning will also be explored as potential moderators. Finally, by repeatedly measuring treatment targets, the investigators will examine time to maximum treatment effect in an effort to understand mechanisms of change.