Studying Crime Trends: Normal Science and Exogenous Shocks*

The study of crime trends has proceeded along two paths: 1) normal science investigations of slow‐moving and tractable changes in crime rates and explanatory conditions and 2) research encounters with unexpected and abrupt changes in crime rates resulting from exogenous shocks. I draw from my research on the relationship between crime rates and changing macroeconomic conditions to illustrate the pains and pleasures of studying crime trends with the tools of normal science. I describe my exploratory investigations of the recent homicide rise in the United States to underscore the theoretical importance and methodological challenges of research on exogenous shocks to crime rates. Finally, I hope to convey to the next generation of criminologists the intellectual excitement that comes from the study of crime trends.