complex social traits. As practical challenges to the inclusion of biological indicators are mastered and as technology rushes ahead, questions of meaning call for ongoing debate.

Like the earlier one, this volume was sponsored by the Behavioral and Social Research Division of the National Institute on Aging and put together under the auspices of the Committee on Population of the National Research Council. Cells and Surveys was influential, but not because the book caused social scientists to add biological measures to their surveys. Doing that was an idea whose time had come. Rather, Cells and Surveys was influential because it provided an authoritative overview of the kinds of biological information that could be collected and how and what the problems and pitfalls were.

In this volume the focus shifts to what has been and can be learned. The authors of most of the chapters have firsthand experience with incorporating biomarkers into social science research and have followed the rapid development of the endeavor. They have thought long and hard about the critical issues. Although there are still many open questions, the time seems ripe for taking stock, not for advocacy but for aspiration to mature judiciousness and nuanced wisdom.

The book emerges from a series of discussions and interchanges that started in 2005 and ended in mid-2007. A workshop, held in June 2006, enabled many of the authors to exchange information and perspectives. Participants in the workshop considered (and the contributions to the book reflect) a few fundamental questions: What has been learned from what has already been done? What is the place of genetic information in social research? What new concepts and methods are being developed or need to be developed?

Biodemography (National Research Council, 1997; Carey and Vaupel, 2005) and its related disciplines have expanded rapidly; one book cannot begin to provide a comprehensive summary of its findings and challenges. We had to pick and choose. Our focus in this volume is on the inclusion of biomarkers in social science surveys: what does (or should) one include and how does (or can) one use the data. The volume grew as we proceeded; in particular, we found ourselves asking more questions about the collection and analysis of genetic information. We also made a conscious choice not to solicit manuscripts on some subjects: notably absent are chapters that specifically focus on ethics. This omission is not because we felt the concerns were unimportant, but because the enormity of the subject made it unfeasible to include. However, both explicitly and implicitly, almost every chapter discusses concerns relating to privacy, informed consent, and the appropriate treatment of study participants and their information.

Hunting for genes that determine health or behavior is not the pre-