The present study examined how dosage and quality of preschool experiences in Head Start (HS) are associated with cognitive and behavioral self-regulation skills in kindergarten. The study included 2,383 children from the Head Start Family and Children Experiences Survey (2009). Using multiple regression (OLS), with multiple imputation methods to address missing data, and propensity score matching to address selection bias, this study examined how the number of hours a week in HS, absenteeism, and number of years (starting at 3-years of age versus at 4-years of age) was related to self-regulation.The study also examined how the quality of classroom experiences, conceptualized as domain-general and domain-specific aspects of teacher-child interactions, was related to self-regulation; and how the quality of teacher-child interactions moderated the relation between dosage and self-regulation. There we two main findings. First, an additional year in HS was the only form of dosage that was significantly associated to self-regulation in kindergarten. Children that attended one more year of HS scored 0.30 points higher on the cognitive self-regulation measure and were scored 0.32 standard deviations higher in behavioral self-regulation, as reported their teachers in kindergarten. Second, quality of domain-general of teacher-child interactions (Responsive Teaching) moderated the relation between hours a week in HS and cognitive self-regulation. In other words, children who participated in classrooms with higher-quality of teacher-child interactions benefited the most from more hours a week in HS. Findings from this study contribute to the growing body of evidence about how dosage and quality of early childhood education experiences relate to child development. Results support the importance of the investment in early childhood education amount and quality for the development of self-regulation.