Self-regulation is an essential ability of children to cope with various developmental challenges. This study examines the developmental interplay between emotional and behavioral self-regulation during childhood and the relationship with academic achievement using data from the longitudinal Millennium Cohort Study (UK). Using cross-lagged panel analyses, we found that emotional and behavioral self-regulation were separate and stable constructs. In addition, both emotional and behavioral self-regulation had positive cross-lagged effects from ages 3 to 7. At an early developmental stage (ages 3 to 5), emotional regulation affected behavioral regulation more strongly than later developmental stages. However, the difference between the reciprocal effects was small from ages 5 to 7. Moreover, behavioral regulation during the third year of primary education (age 7) had a substantial and positive effect on teachers' evaluations of educational achievement during the last year of primary school (age 11). In contrast, emotional self-regulation only had a small indirect and positive effect via behavioral self-regulation. The current study suggests the structure of self-regulation was multidimensional and its facets are mutually dependent in the child's development. In order to gain a complete picture of the development of self-regulation and its effect on educational achievement, the facets emotional and behavioral regulation should both be studied in concert.