Symmetry breaking events are required for cell division, development, and movement in all organisms from single-celled species to human beings. Moreover, in multicellular organisms, symmetry breaking allows the generation of cells with different fates and underpins the complex arrangement of tissues and organs achieved during embryogenesis. This volume includes discussions of the molecular basis of polarization mechanisms, asymmetric division of stem cells during development, the generation of left-right asymmetry of the body axis in mammals, and theoretical approaches to symmetry breaking. It is geared towards molecular, cell, and developmental biologists, as well as physical scientists interested in how and why symmetry breaking occurs in living systems.