The report was produced by Fight Crime: Invest in Kids Pennsylvania, a nonprofit organization of police chiefs, sheriffs, and prosecutors. Williams sits on the group's board.
The problem, organizers say, is that the government spends too much on prisons and not enough on preschool. In Pennsylvania, about $2.3 billion is spent annually on corrections; $340 million is spent on early childhood programs.
That has long-term ramifications, Williams said in an interview.
Students who lack good preschool programs may have trouble with key lessons - "Don't bite people. Don't take their toys. Don't shoot people. Don't steal their cars," Williams said. "Children need to learn conflict resolution, and that starts in pre-K. Children need to learn how to deal with their anger, and that starts in pre-K."
At-risk children not enrolled in a high-quality preschool were five times more likely to be serial offenders by age 27, according to a long-term study of one Michigan early childhood center; a Chicago study found that at-risk children were 70 percent more likely to be arrested for a violent crime by age 18.
Researchers estimate that strong preschool programs provide $11 in benefits for every $1 invested - $5 of which comes from less money spent on crime and corrections.
In Philadelphia, as in many cities, there are far more needy children than spots in good preschools. More than 3,000 low-income city children remain on waiting lists, according to the Philadelphia School District.
Statewide, 17 percent of 3- and 4-year-olds are enrolled in high-quality, publicly funded preschool programs.
Williams and others exhorted Gov. Corbett and state legislators to expand early childhood funding, and cautioned that only high-quality programs - those with skilled teachers, age-appropriate curricula, low child-to-teacher ratios, and screening for developmental and behavioral problems - should be invested in.
While the main thrust of his job is prosecution, Williams said, advocating for causes like this one could someday make his job easier.
"I believe we have to be smart on crime," Williams said. "Not just talk tough."
Contact Kristen Graham at 215-854-5146, firstname.lastname@example.org or on Twitter @newskag. Read her blog, "Philly School Files," at www.philly.com/schoolfiles.