Conscious Discipline is a classroom management program that targets relationship building and socio-emotional learning to improve students' academic performance, as well as executive function (EF) and social skills. Past studies evaluating the effectiveness of this program, however, are limited and have yielded mixed results. The purpose of this study was to examine the relationship between preschool teachers' Conscious Discipline fidelity and students' kindergarten readiness and social skill development. This study included 873 preschool-aged students from 146 classrooms that used the Conscious Discipline program. We found that Conscious Discipline fidelity was significantly associated with students' EF skill gains, which in turn predicted outcomes on students' overall kindergarten readiness scores as well as their scores on evaluations of their language and literacy, math, social foundations, and physical development specifically. Results suggest that EF skill development mediates the relationship between preschool teachers' Conscious Discipline fidelity and students' kindergarten readiness scores.