When it comes to studying the nature and origin of differences between men and women, one quickly encounters an aggressive cacophony of politics. Often, the scientists themselves are the most egregious perpetrators of this confusion, selectively coloring and distorting findings to suit their personal agendas.
The fact is, there is an overwhelming amount of science addressing sex differences. And no single book does a better job of communicating the bulk of this science in a neutral fashion than Sex Differences in the Brain. As SDintB asserts early on, accurate knowledge of sexual dimorphisms in the brain isn't just a political or philosophical issue, but a health issue: men and women suffering from multifarious sources of neural and psychiatric debilitation may require different treatment depending on their gender. This is a point often overlooked in the rush to insist that men and women are fundamentally the same in the brain.
Make no mistake: this is an academic book, aimed at scholars. It's dense with invaluable references, with chapters authored by a variety of scientists from a respectably wide diversity of disciplines. It covers almost every major area of sex differences: genetic, behavioral neuroendocrinology, neurocognition, neuroplasticity, neurophysiology, psychiatry, pharmacogenetics, stress response. The chapters are quite thorough, and generally review the available research in a neutral fashion.
There's probably no better place to start an inquiry into what truly makes men and women different than Sex Differences in the Brain.