Background: In France, 3.2 million middle-school students have serious/persistent school difficulties and are re-engaged in adapted-general/vocational-education class (AGVEC), created to early re-engage them in school/professional projects. We assessed the AGVEC's benefits for school-behavior-health-related difficulties (SBHDs). Methods: This population-based study compared 83 AGVEC students (mean age = 14.4 ± 1.1) with 1559 regular-class students (mean age = 13.5 ± 1.3) from north-eastern France. They completed a questionnaire collecting socioeconomic features and SBHDs. The data were analyzed using logistic regression models and Kaplan-Meier estimates. Results: The AGVEC students had similar academic performance but fewer school absences due to health problems, less sleep difficulty, fewer depressive symptoms, and more social support as compared with regular-class students: sex-age-class-level-adjusted odds ratio (saclOR) 0.31-0.56 (p < 0.05/0.001). The AGVEC students had fewer skipping school, better health status, less sleep difficulty, fewer depressive symptoms, fewer suicide ideation/attempt, and more social support as compared with regular-class students with low academic performance: saclOR 0.22-0.52 (most with p < 0.01). Socioeconomic features played modest roles. The benefits for depressive symptoms and suicide attempt increased with age since age 10. Conclusions: Re-engagement in the AGVEC is particularly effective in reducing SBHDs.