The report shows an estimated 1 million elementary school-age students were absent last year. State officials say that could cost the state billions of dollars in increased crime and poverty.
Seven days' absence makes a big difference to both the child and the California economy, according to a study by the California Department of Justice.
"In terms of public safety, social services, public health, costs California $46 billion a year," said state Attorney General Kamala Harris.
Attorney General Kamala Harris says dropouts are more likely to end up in prison or become victims of crime.
Some counties have responded by launching crackdowns going after parents of truant teenagers.
But the report suggests that the habit of regular attendance needs to start way before middle school.
"Children as young as 5 years old who are missing enough school so that they will have a serious setback in terms of their ability to ever be adequately educated," said Harris.
Harris told leaders Monday that public policy is partly to blame. California is one of four states that does not require tracking of absenteeism on a student-by-student basis.
The Los Angeles Unified School District does track, and it says it's more than poverty that causes truancy.
"We have parents that are mentally ill, as well as children that are mentally ill, so there is domestic violence, there's substance abuse," said Debra Duardo, executive director of LAUSD Student Health and Human Services. "There are many other issues that prevent students from coming to school, or prevent parents from being able to take their children to school."
In the 2011-2012 school year, San Bernardino County had the highest truancy rate, at 28.3 percent. Riverside County was at 23.9 percent. Los Angeles County had 20.5 percent. Ventura County was at 16.7 percent. Orange County was at 12.3 percent.
LAUSD now has programs that reward students for improved attendance, and provides support programs for parents.
"We want to help you. We want to know what the issues are, and we want to connect you to the resources so that you can get help," said Duardo.
This is the first year the attorney general has issued such a report. Harris says there will be more. She plans to compile the figures in subsequent years for as long as she is in office.