Based on the 20 year experience of using the Twin Block appliance for the correction of Class II malocclusion with mandibular deficiency in the Department of Paediatric and Preventive Dentistry ,A.b Shetty Memorial Institute of Dental Sciences, this book is a comprehensive and highly illustrated clinical and practical guide on the use of the Twin Block Appliance and its recent advances and modifications. The book gives an overview on the mechanism of action of the appliance from its clinical to the molecular level with emphasis on the changes brought by the appliance on the mandibular condyle and masticatory muscles, case selection parameters, appliance design and modification, chair side management of the appliance and finally the post treatment changes to be expected- skeletal, dental and soft tissue with an additional note on pitfalls that could be encountered during the treatment duration and its management strategies.