Dismantle or Defuse? shows how two evidence-based approaches— Inference-based Cognitive Behavioral Therapy (I-CBT) and Acceptance and Commitment Therapy (ACT)—tackle obsessive doubt, mental rituals, and the “what-if” loop in OCD and obsessional thinking. Part One: I -CBT explains inferential confusion, the feared-self theme, and reality-sensing steps that help you spot when imagination is posing as fact. Part Two: ACT teaches defusion, values, and committed action so you can change how you relate to sticky thoughts without arguing with them. Side-by-Side Tools : clear checklists to decide when to use I-CBT dismantling and when to use ACT defusion, plus sample scripts, tracking sheets, and relapse-prevention plans. Everyday Examples: contamination, checking, harm doubts, relationship doubts, and “not-just-right” sensations, with practical exercises you can try at your own pace. By the end, you’ll have a simple method to choose the right tool for the moment: dismantle doubtful stories with I-CBT or defuse sticky thoughts with ACT—then return to meaningful action. Who it’s for: adults, students, and clinicians seeking a plain-English, step-by-step guide that respects science and focuses on usable skills. Key topics: I-CBT, ACT, inferential confusion, cognitive fusion, mental rituals, reassurance seeking, values-based action, reality-sensing, obsessional doubt, self-help for OCD.