A key indicator of high school success is eluding one of the largest student populations in Montgomery County, putting principals and parents on alert and in search of new solutions for a growing problem.

The benchmark is maintaining a C average — a level of performance required for most extracurricular activities and widely regarded as the hook that keeps students engaged in school. Hispanic students, who make up more than 20 percent of the district’s population and who have increased in number every year since 1980, are less likely than any of their peers to hold to that minimum.