OCD Is a Reasoning Problem. Not an Anxiety Problem. Most OCD treatments enter the cycle after the obsessional doubt has already formed. They teach tolerance, avoidance of avoidance, or cognitive restructuring of the thought that arrives. None of them ask where the doubt came from in the first place. Inference-based cognitive behavioral therapy — I-CBT — does. This workbook introduces I-CBT through a structured 30-day practice plan that targets the reasoning process that manufactures obsessional doubt before anxiety ever forms. A Different Starting Point Inferential confusion is the specific reasoning error at the core of OCD. It occurs when the mind abandons what the senses directly report and substitutes an imagined scenario instead. I-CBT addresses this substitution at the source. The result is an approach that works upstream of the doubt, at the step in the sequence where the problem is actually being made. What the 30-Day Plan Builds Working day by day, readers map their own obsessional sequence, identify the five borrowed sources OCD uses to build its case, locate the exact crossover moment where reality ends and imagination begins, and develop a personal alternative story grounded in direct evidence. The final week introduces the Real Self Portrait — a document built from demonstrated values and behavioral patterns — that stands in direct contrast to the feared identity OCD has been threatening to reveal. Covers Every Major OCD Subtype Separate chapters address contamination OCD, checking OCD, harm OCD, relationship OCD, pure-O and intrusive thoughts, and scrupulosity. Each subtype section maps the specific reasoning patterns, Vulnerable Self-Theme, and application of the core tools to that presentation. For Adults Who Have Tried Other Approaches This plan is designed for adults with any OCD subtype, for people who completed ERP and still cycle, and for neurodivergent individuals who found uncertainty-tolerance approaches difficult to sustain. A dedicated chapter addresses how I-CBT relates to ACT, to SSRI medication, and to autistic and ADHD presentations of OCD.