Available to purchase for Students. This 60 minute webinar was presented by Prof Robyn Tate. Synposis: This practical “how to” webinar builds on information presented in Part 1 of this series. It assumes the delegate has knowledge of basic concepts pertinent to single-case design (SCD) methodology, the common types of designs, a procedure to implement a SCD, and a framework for using single-case methods in clinical practice. This webinar focuses on how to ensure a SCD is scientifically sound. It first addresses threats to internal validity and how they apply to SCDs. It then describes Standards of Design as published by the What Works Clearinghouse (WWC). The third section presents the internal validity subscale of the Risk of Bias in N-of-1 Trials Scale and shows how it can be used in the planning stage of a study to maximise scientific rigour and minimise threats to internal validity. Finally, the webinar concludes with a description of WWC Standards of Evidence for establishing evidence-based treatments. Webinar outcomes: at the end of this webinar, delegates will have knowledge of: 1. common threats to internal validity as encountered in SCDs; 2. the four WWC Design Standards for SCDs; 3. the seven internal validity items of the Risk of Bias in N-of-1 Trials Scale and how they can be used to minimise threats to internal validity; and 4. WWC Standards of Evidence. Target audience: researchers; clinicians in allied-health and medicine; advanced students