This volume highlights major contributions that identify new developments and directions in the field over the past decade, as well as challenges for the foreseeable future. An integration of information from laboratory and epidemiological studies, male reproduction and teratology can be found throughout the volume. The range of topics include parental legacies and genomics, lifestyle, occupational and therapeutic paternal exposures and effects; effects on the gamete-packaging of human sperm; role of DNA repair and germ cell apoptosis; stem cells, epigenetics and closing; model systems and implications to clinicians and general counselors.