More than 25 percent of the students enrolled in Head Start programs in D.C. Public Schools were chronically absent last school year, missing at least 10 percent or the equivalent of a month or more, according to two reports the Urban Institute plans to release Tuesday.

Seven percent of the students missed 20 percent or more of enrolled days.

Overall, less than half — 44 percent — of the school system’s Head Start students had what one report called “satisfactory attendance,” which is missing 5 percent or less of the school year.

School attendance in the District is not compulsory until kindergarten, but school officials said they hope to maximize the city’s hefty investment in universal preschool by increasing efforts to ensure that children attend, preparing them to start kindergarten with good attendance.

Research shows that early attendance problems often persist, putting children at greater risk of performing poorly on math or reading tests in elementary school, repeating a grade or dropping out of school.

“We are trying to get the message out that Pre-K is not child care,” said Deborah Paratore, director of Head Start program operations for D.C. Public Schools. “It’s a place where habits are formed, where children are going to school.”

The study looks at Head Start programs in the city’s traditional public schools, which enroll more than 5,000 preschool-age students, or about 40 percent of all children enrolled in the city’s publicly funded preschool programs for 3-year-olds and 4-year-olds.

The District offers Head Start programs in schools with high concentrations of students in poverty, using a mix of federal and local funds to provide extra staffing and support services for all children and families enrolled, regardless of income eligibility.

While absenteeism in the programs is high, the report showed that attendance is improving. The percentage of students with satisfactory attendance increased from 36 percent in the 2012-2013 school year to 44 percent last year, which researchers saw as a reflection of the school system’s increased focus on attendance.

Improving K-12 school attendance has become an increasing priority for school districts across the country, but only a few districts have focused attention on the preschool years.

Other studies of preschool absenteeism have found comparable rates in Baltimore and higher rates in Chicago (where 45 percent of 3-year-olds and 36 percent of 4-year-olds were considered chronically absent) and New York (where the rate was closer to 50 percent).

The D.C. study counted both excused and unexcused absences on the premise that any time away from school has an effect on a child’s ability to learn.

Homeless children were the most likely to miss school, followed by children enrolled in the Temporary Assistance for Needy Families program. African American children also have a high rate of absenteeism.

Attendance rates varied by day of the week, with higher rates of absenteeism near weekends.

On average, 8 percent of students missed school on Mondays, and 9 percent missed school Fridays.

Rates also varied by months of the year: In January and June, 10 percent of students were out, compared with 5 percent and 6 percent, respectively, in September and October.

A companion report recommended steps the District can take to improve attendance, starting with raising awareness among families that school attendance matters, even for the city’s youngest students.

Many barriers to good attendance reflect more difficult social and economic challenges for families and are tougher to resolve.

Paratore said the District has prepared a pamphlet for families that includes information about strategies for improving attendance. Starting in 2012, when a child missed three days of school, the case was referred to a family services worker.

In the past, a child had to miss three consecutive days before he or she would be flagged for potential attendance problems. The absences could trigger a phone call or home visit, or referral to a case manager for more services.

The report credited increased family engagement for driving improvement in attendance, though it also noted that it has created a large jump in caseload for family services workers. About 80 percent of all students enrolled accumulated three or more absences.