Although high school graduation rates are improving, many students are still not successful. Research has documented that 9th grade is a pivotal year in determining whether a student will graduate or drop out. The purpose of this randomized controlled trial was to assess the effects of a Tier 1 intervention model (freshmen success) for 9th grade students to increase school engagement, attendance, credits earned, and grade point average (GPA). This study included 1,588 students in ninth grade across 4 comprehensive high schools. Treatment schools implemented the freshmen success components: a 9th grade leadership team, a curriculum, and support from peer navigators. Control schools continued business as usual. Results showed statistically significant and educationally meaningful effects on student motivation, engagement and attendance, and a moderate-to-large effect for credits earned. However, there was no significant effect found for GPA.