Challenges with numerical proficiency at an early age can lead to substantial gaps in learning and are associated with detrimental long-term outcomes. In addition, students with emotional-behavioral disorders (EBD) can have some of the most challenging behavioral and academic needs to address. The purpose of this study was to identify the effects and collateral outcomes of utilizing cross-age tutors (i.e., older students) with/at risk of EBD to deliver a number line board game intervention to kindergarten students at risk of mathematics disabilities. A multiple baseline design across participants was utilized to evaluate the following research questions: (a) What are the effects of a number line game delivered by a cross-age tutor with EBD on the mathematics performance of kindergarten students with mathematics difficulties? (b) Can students with EBD implement tutoring procedures with fidelity? (c) What are the effects of the cross-age tutoring training and implementation on the tutors' classroom behaviors and risk-status for EBD? Tutoring sessions took place for 25-30 min, 3 times per week, over 10 weeks. Results suggest cross-age tutoring to be an effective and feasible model for improving mathematics performance of at-risk kindergarteners and, to a lesser extent, the behavioral performance of students with EBD.