North Carolina's Early College model is the subject of an IES-funded eleven-year longitudinal experimental study that utilized a lottery process to assign early college applicants to either treatment or control groups. This paper presents findings related to high school outcomes. The primary goal of the early college model is to increase the number of students who graduate from high school and who continue on to and succeed in college. The specific research questions addressed in this paper include the following: (1) What is the impact of the early college model on the percentage of students successfully completing a college preparatory course of study in high school? (2) What is the impact of the early college model on the number of college credits earned while in high school? (3) What is the impact of the early college model on students' graduation from high school? (4) How does the impact vary for specific sub-groups including those who are low-income, first in their family to go to college, members of underrepresented minority groups, and those who entered high school below grade level? Results from this study show that the Early College High School model is having positive impacts on students' college preparatory course-taking, their attainment of college credits, and their graduation from high school. Tables and figures are appended. [For the related article: "The Small, Stand-Alone Early College: Impact on Postsecondary Outcomes," see ED567041.]