Accelerated partial breast irradiation (APBI)' is being rapidly introduced into the clinical management of early breast cancer. 'APBI', in fact, encompasses a number of different techniques and approaches that include brachytherapy, intraoperative, and external beam techniques. There is currently no single source that describes these techniques and their clinical implementation. This text will be a concise handbook designed to assist the clinician in the implementation of 'APBI'. This will include a review of the principles that underlie 'APBI', a practical and detailed description of each technique for 'APBI', a review of current clinical results of 'APBI', and a review of the incidence and management of treatment related complications.