Children of the Prison Boom: Mass Incarceration and the Future of American Inequality. By Sarah Wakefield and Christopher Wildeman. New York: Oxford University Press, 2014. 231 pp. $34.95 doth.In his majority opinion in United States v. Windsor (2013), Justice Anthony Kennedy offered a novel argument for invalidating the federal refusal to recognize same-sex marriages. The Defense of Marriage Act, Kennedy explained, humiliates children raised by same-sex couples. Many regulatory schemes, whether civil or criminal, have spillover effects onto the children of regulated subjects. Judicial acknowledgement of those effects in the same-sex marriage context, however, contrasts strikingly with the judicial incuriosity about parallel effects in other domains, particularly in the criminal law.Since the 1970s, the United States has experienced explosive growth in incarceration. Mass incarceration unequally affects different racial groups. Black men lacking a high school diploma are more than five times more likely to be incarcerated, for example, than similarly situated white men (p. 15). One in four black children in the 1990 cohort experienced paternal incarceration (p. 41). Does mass incarceration humiliate, or inflict worse harms, on children? And does the effect differ by racial group in ways that influence larger patterns of racial inequality?The answers are not obvious. The incarcerated population is drawn from a relatively narrow slice of the left-tail of the income distribution. Its direct effect on inequality is tightly bounded. Western, for example, estimated the effect of incarceration on the gap between black and white earnings to be around three percent (Western 2006). Further, parental incarceration might have no effect if it is caused by the same underlying factors that cause other undesirable childhood outcomes (e.g., poverty, health problems, and homelessness). Alternatively, parental incarceration might enhance the welfare of children by removing a source of violent risk and criminality from the household.Documenting the causal effect of parental incarceration on childhood outcomes raises nettlesome methodological problems: Randomized experiments are out of bounds. Few large-scale data-sets contain extensive longitudinal evidence. Existing data presents significant identification problems. The central contribution of Children of the Prison Boom is the application of sophisticated econometric methodologies to a range of national and city-level data to generate deeply sobering evidence of incarceration's devastating effect on children, and in particular African-American children. Focusing on the causal effects of (largely paternal) incarceration on children's mental health, behavioral outcomes, homelessness, and infant mortality, Wakefield and Wildeman also persuasively demonstrate that mass incarceration is a significant causal pathway for the intergenerational reproduction of racial inequality.To generate estimates of parental incarceration's causal effects, Wakefield and Wildeman rely on three large longitudinal datagathering efforts: the twenty-city Fragile Families and Child Wellbeing study, the single-city Project on Human Development in Chicago Neighborhoods, and the multistate Pregnancy Risk Assessment Monitoring Systems. Longitudinal data allows them to deploy propensity-score matching, within-person change models, and synthetic regressions to estimate the average effect of parental incarceration on outcomes of interest. In respect to each independent variable of interest, Wakefield and Wildeman apply different methods and present several model specifications. By generating estimates of causal effects that are robust to both method and model specification, they generate powerful evidence of causality. …