After providing an outline of the contents of this book, the chapter considers recent history relevant to the debate on women in science. It discusses the evidence-based grounds for a biologically based argument in a number of the essays in this volume. The chapter describes the need for this volume. The essays in this volume show that the pattern of sex differences is much more nuanced than their depiction in the popular media (e.g., male=right brain; female=left brain). Notwithstanding the impressive progress girls and women have made in pursuing coursework and graduate degrees in science and mathematics in recent years, however, the increased representation of women among doctoral recipients has not coincided with increased faculty representation in some scientific and engineering fields.