This paper examines the associations between attendance at early childhood education (ECE) and longer-term academic attainment and socioeconomic wellbeing in a New Zealand birth cohort studied to age 30. Nearly 95% of the cohort had attended ECE by age 5. After adjustment for family background and child characteristics, results showed statistically significant trends for increasing duration of ECE attendance to be associated with: greater attainment of high school and university qualifications and higher adult socioeconomic wellbeing (income, employment, occupational status); effect size estimates were small to moderate. No evidence was found for differential effects of ECE attendance across subgroups defined by child: ethnicity, gender, parental education or socioeconomic status. The implications of these findings are discussed.