This book collates past and current research on one of the most promising emerging modalities for breast cancer detection. Readers will discover how, as a standalone technology or in conjunction with another modality, microwave imaging has the potential to provide reliable, safe and comfortable breast exams at low cost. Current breast imaging modalities include X- ray, Ultrasound, Magnetic Resonance Imaging, and Positron Emission Tomography. Each of these methods suffers from limitations, including poor sensitivity or specificity, high cost, patient discomfort, and exposure to potentially harmful ionising radiation. Microwave breast imaging is based on a contrast in the dielectric properties of breast tissue that exists at microwave frequencies. The book begins by considering the anatomy and dielectric properties of the breast, contrasting historical and recent studies. Next, radar-based breast imaging algorithms are discussed, encompassing both early-stage artefact removal, and data independent and adaptive beamforming algorithms. Similarly, microwave tomographic reconstruction algorithms are reviewed, introducing the reader to both the fundamental and more advanced algorithms. The book also reviews research efforts to extract clinically useful information from the radar target signature of breast tumours. Finally, the book concludes by describing the state of the art prototype microwave breast imaging systems, with a particular emphasis on those which have progressed to the clinical evaluation stage. This work is motivated by the fact that breast cancer is one of the leading causes of death amongst women in Europe and the US, and the second most common cancer in the world today. Such an important area of research will appeal to many scholars and practitioners.