Objectives: Focused thoracic ultrasound (TUS) provides an increased safety profile when undertaking invasive pleural procedures. This has led to the requirement for defined curricula, high quality teaching and robust, validated assessment tools among physicians to ensure patient safety and clinical excellence. Current UK practice is based almost exclusively on expert consensus, but assessment methods employed have been shown to have low reliability and validity and are potentially open to bias. As a result, several assessment tools have been developed, although each has its own limitations. Methods: This study aimed to develop and validate an assessment tool corresponding to those skills associated with the most basic level of practice, defined recently as an emergency level operator in the British Thoracic Society Training Standards for Thoracic Ultrasound.Results: A total of 27 candidates were enrolled by two examiners based in Belfast and Oxford over a 10-month period between February and November 2019. Mean score of the inexperienced group was 44.3 (95% CI 39.2-49.4, range 28-54) compared with 74.9 (95% CI 72.8-77, range 64-80) in the experienced group providing an estimated mean difference of 30.7 between the two groups (95% CI 24.7-36.7; p < .001).