This volume covers three main themes of research into sex differences in basic neurobiology, psychology, preclinical research and clinical research. It begins by exploring our understanding of sex and gender in relation to both animal and human behaviors and discusses the relevance, and importance, of considering sex and gender when conducting research into brain function and behaviors. The second theme focuses on how sex and gender influence mentalhealth and considers the impact of our immune system and the changes that occur with ageing. Finally, the third aspect focuses on examples of neurological disorder which show sex differences in terms of their aetiology and/or symptomology and considers the relevance in the development of treatment for these disorders including dementia, stroke and multiple sclerosis.