Yesterday, the Civil Rights Project released a new report, The High Cost of Harsh Discipline and Its Disparate Impact.  The study attempts to quantify the cost of harsh school discipline through the dropouts and social costs it produces.  It looks closely at California and Florida to create a baseline of costs and then extrapolates them nationwide.  The abstract explains:

School suspension rates have been rising since the early 1970s, especially for children of color. One body of research has demonstrated that suspension from school is harmful to students, as it increases the risk of retention and school dropout. Another has demonstrated that school dropouts impose huge social costs on their states and localities, due to lost wages and taxes, increased crime, higher welfare costs, and poorer health. Although it is estimated that reducing school suspension rates in Texas would save the state up to $1 billion in social costs, only one study to date has linked these two bodies of research. The current study addresses some of the limitations of that study by (1) estimating a stronger causal model of the effects suspension has on dropping out of school, (2) calculating a more comprehensive set of the social costs associated with dropping out, and (3) estimating the cost of school suspensions in Florida and California, and for the U.S. as a whole. The results show that suspensions in 10th grade alone produced more than 67,000 dropouts in the U.S. and generated social costs to the nation of more than $35 billion. These results are undoubtedly conservative, since the California and U.S. estimates were limited to 10th-grade students, while the Florida estimates were limited to 9th-grade students. Thus, they did not capture the effects of suspensions in earlier grades.

The study is reminiscent of (albeit distinct from) a 2013 report by law enforcement officials titled I'm the Guy You Pay Later.  That report emphasized that a 

10-year investment in preschool will produce over 2 million additional high school graduates. And if we can reduce the number of young people who commit felonies and the number who are incarcerated by 10 percent each – roughly half the reduction achieved by the Chicago Child-Parent Center program – we can reduce the number of individuals who are locked up by 200,000 each year. The resulting savings – $75 billion over the 10-year investment – could pay the federal costs of the preschool program.

Together, these two studies further the core thesis of my book, Ending Zero Tolerance, which is that school quality and discipline are inextricably intertwined.  A primary solution to school quality failures is improving the school discipline system (which means taking approaches that are the opposite of zero tolerance) and a primary solution to school discipline is improving school quality and services.  The back-end payoffs are enormous.  Unfortunately, the dominant narratives treat these issues as separate and distinct.