This chapter examines issues of gender and security. It begins with an explanation of what we mean by gender and explains why issues of gender are central to understanding security. International Relations specialists have over the last three decades explored and interpreted the ways in which men and women have responded to the national and international policies which have governed conflict, terrorism, and war. The chapter demonstrates that through understanding and placing notions of gender at the centre of any debate on security one can unleash a series of interlocking understandings of the way men and women relate to insecurity, violence, and war.