Across the United States, enrollment in high school computer science (CS) courses is increasing. These increases, however, are not spread evenly across race and gender. CS remains largely an elective class, and fewer than three-fourths of the states allow it to count towards graduation. The Chicago Public Schools has sought to ensure access for all students by recently enacting computer science as a high school graduation requirement. The primary class that fulfills the graduation requirement is Exploring Computer Science (ECS), a high school introductory course and professional development program designed to foster deep engagement through equitable inquiry around CS concepts. The number of students taking CS in the district increased significantly and these increases are distributed equitably across demographic characteristics. With ECS serving as a core class, it becomes critical to ensure success for all students independent of demographic characteristics, as success in the course directly affects a student's ability to graduate from high school. In this paper, we examine the factors that correlate with student failure in the course. At the student level, attendance and prior general academic performance correlate with passing the class. After controlling for student characteristics, whether or not teachers participated in the professional development program associated with ECS correlates with student success in passing the course. These results provide evidence for the importance of engaging teachers in professional development, in conjunction with requiring a course specifically designed to provide an equitable computer science experience, in order to broaden participation in computing.