This study examined interrelationships of changes in compulsive behaviours and two levels of belief over treatment of obsessive-compulsive disorder (OCD). Levels were individual-specific obsessive beliefs (termed here manifest beliefs) and OCD-relevant general beliefs. If OCD-relevant general beliefs are functionally linked to manifest beliefs and compulsive behaviours, changes in compulsive behaviours and both belief types should occur mostly in tandem, even if only one or two of these three elements are explicitly targeted. Baselines consisting of time performing compulsive behaviours, strength of manifest belief and strength of OCD-relevant general beliefs were monitored daily by six participants over three phases in an A/B/B + C design. (A = no treatment, B = exposure/response prevention and C = cognitive therapy targeting only OCD-relevant general beliefs.) Changes in compulsive behaviours, manifest beliefs and OCD-relevant general beliefs moved primarily in tandem over treatment phases, suggesting functional links between these elements.