New research contains a message for high school students, especially low-income ones, who want to go to college: Take the SAT early and often.

It’s already clear from earlier studies that lack of information is a big reason many less affluent students don’t make it to college. They get less help navigating the complex process of applying. A new study finds another specific instance of this: Underrepresented students are less likely to take college admission tests more than once.

Encouraging them to retake tests — as many of their high-income, white and Asian-American peers do — could close a substantial portion of the income and racial gap in enrollment at four-year colleges. That’s the conclusion of a working paper released on Monday by Joshua S. Goodman, Oded Gurantz and Jonathan Smith.

The three economists studied over 10 million students who took the SAT reasoning test, one of two standard college admissions exams (along with the ACT), and analyzed the effect that retaking the exam had on the students’ subsequent scores and college prospects.