Scabies is a common parasitic skin condition that causes considerable morbidity globally. Clinical and epidemiological research for scabies have been limited by a lack of standardisation of diagnostic methods. We aimed to develop consensus criteria for the diagnosis of common scabies that could be implemented in a variety of settings. Consensus diagnostic criteria were developed through a Delphi study of international experts. Detailed recommendations were collected from the expert panel to define the criteria features and guide their implementation. These comments were then combined with a comprehensive review of available literature and opinion of an expanded group of international experts to develop detailed, evidence-based definitions and diagnostic methods. The 2020 IACS Consensus Criteria for the Diagnosis of Scabies include three levels of diagnostic certainty and eight subcategories. Confirmed Scabies (Level A) requires direct visualisation of the mite or its products. Clinical Scabies (Level B) and Suspected Scabies (Level C) rely on clinical assessment of signs and symptoms. Evidence-based, consensus methods for microscopy, visualisation and clinical symptoms and signs were developed, along with a media library. The 2020 IACS Criteria represent a pragmatic, yet robust set of diagnostic features and methods. The criteria may be implemented in a range of research, public health and clinical settings by selecting the appropriate diagnostic levels and subcategories. These criteria may provide greater consistency and standardisation for scabies diagnoses. Validation studies and development of training materials and development of survey methods are now required.