Most peoples ideas about crime come from headlines, TV shows, and politically biased conventional wisdom. Robert Sampson is a pioneer in sophisticated, evidence-based analyses of crime, and here he explores a profound but underappreciated fact about trends: they can reflect a changing zeitgeist, a shifting mixture of ages, or a turnover of generations. Sampson deftly disentangles them and presents a new understanding of the dramatic changes in American crime rates. -- Steven Pinker, author of The Better Angels of Our Nature: Why Violence Has Declined A landmark achievement from Rob Sampsonbold, incisive, and destined to reshape conventional thinking across public policy, law enforcement, and the social sciences. This is an instant classic. -- Bruce Western, president, Russell Sage Foundation Rob Sampson is criminologys leading researcher: an innovative social scientist who has, time and again, improved the fields methodology, data-gathering, and theory. Marked by Time once again breaks new ground this time by demonstrating the striking significance for birth-cohort studies and for criminological theorizing of the interaction between historical change and individual development. A major contribution! -- David Garland, author of Law and Order Leviathan: Americas Extraordinary Regime of Policing and Punishment