Local high schools that participate in the Metco program are redoubling efforts to challenge and equip all students to achieve top MCAS scores, officials said, after recent test results showed African-American students in the regional collaboration persistently lagging behind their white classmates.

In most area school districts that participate in the voluntary school-integration program, the vast majority of 10th-graders of all races scored at least “proficient” on the MCAS exams taken last spring. But a Globe review of the data found a stark gap between students of different races who achieved “advanced” scores.