This book is aimed at the undergraduate dental student, the general dental practitioner with an interest in orthodontics and students at the start of their postgraduate orthodontic training. The book assumes the reader has progressed down the path of orthodontic diagnosis and is in the process of formulating a treatment plan. Such planning requires the orthodontist to have a sound understanding of the biological principles of tooth movement, as well as to be aware of the treatment ideals and limitations. Knowledge of the various types of orthodontic appliances, their design and likely mode of action is also essential. Closely linked to this, advances in materials science have lead to great changes in orthodontic clinical practice in recent years. A chapter on orthodontic materials is therefore included. Orthodontic treatment is not without risk and there is a chapter on iatrogenic effects. Finally, with increasing specialisation there is a need to call upon the services of colleagues from other specialities in treating complex cases and so multidisciplinary treatments are also covered.