BOSTON – In a quarter of Massachusetts public high schools last year, less than 60 percent of seniors took the SAT exam – leaving the rest without the test results many colleges require to gain admittance.

Almost 81 percent of the nation’s colleges and universities use the SAT for admission, according to the College Board, which owns the test.

“These are kids that are going to be low-wage workers unless they take the SAT,” said Miren Uriarte, director of the GastDon Institute for Latino Community Development and Public Policy at the University of Massachusetts at Boston. “The kids that are not aware of all the options are sort of left behind.”

Massachusetts has one of the highest SAT participation rates in the country, with 79 percent of graduating seniors taking the test last year.

But The Boston Globe, which reviewed state records from 2003-06, reported Monday that schools in affluent cities and towns have higher testing rates that boost the state average. Twenty-nine schools tested all their seniors. Most were in wealthy towns or were small, urban charter schools or Boston’s elite exam schools.

Many of the schools with lower rates, meanwhile, serve the state’s poorest students and have high enrollment of black or Hispanic students. Schools in Lawrence, Holyoke and Chelsea barely had half of their students take the exam.

“As much as we brag about the high percentage of kids who take the SAT, we are concerned about the minority and poor kids who don’t,” Education Commissioner David Driscoll said.

Researchers say high schools vary widely in how much focus is put on college preparation. Some try to send nearly all students to four-year colleges, while others focus on a small percentage of students.

In Somerville, which has a majority of low-income students, half of students take the SAT. Guidance supervisor Carolyn Richards said she wants the rate to be closer to 70 percent.

This year, the school is offering free on-campus SAT prep classes to juniors and seniors in an effort to boost test rates. Guidance counselors are personally inviting students to enroll.

Manpreet Pabla, a 16-year-old junior, said the school’s guidance was key because her parents are immigrants from India and unfamiliar with the American college system.

“I told my mom,” Pabla said of the SAT. “She just knows it’s a test. She doesn’t know a lot about it.”