Birth order and educational achievement in adolescence and young adulthood David M. Fergusson L. John Horwood Joseph M. Boden Christchurch School of Medicine and Health Sciences Introduction A large body of research has examined linkages between birth order and later psy- chological outcomes including mental health, intelligence, academic achievement, and personality (for reviews see Elliott, 1992; Heer, 1985; Steelman, Powell & Werum, 2002; Stewart & Stewart, 1995; Zajonc, 2001; Zajonc & Mullally, 1997). One aspect of this research has been an examination of the linkages between birth order and educational achievement. In general, this research has led to the con- clusions that later birth position is associated with lower educational achievement and career outcomes. For example, Black, Devereux and Salvanes (2005) examined the effects of birth order on educational achievement, using a sample consisting of the population of Norway,and found that earlier birth position was associated with a significantly greater number of years of education. Similarly, Herrera and col- leagues (Herrera, Zajonc,Wieczorkowska & Cichomski, 2003), using data from a large representative cross-sectional sample in Poland, found that first- and earlier- born respondents reported a significantly greater number of years of schooling and higher levels of occupational prestige.Also,Travis and Kohli (1995) reported that earlier birth order was related to the total number of years of education, particul- arly for those individuals from middle-class families.These results were replicated T his paper examines the relationship between birth order and later edu- cational outcomes in a birth cohort of more than 1,000 New Zealand young adults studied to the age of twenty-five. Being later born was associated with gaining fewer educational qualifications at secondary level and beyond. The use of nested models to control for the confounding effects of family size on birth order revealed that birth order effects on educational attainment were not disguised by family size effects. Following adjustment for potentially confounding factors, there remained a statistically significant association between being later born and a lower likelihood of obtaining educational qualifications. It was concluded that the intra- family dynamics initiated by birth order may have a lasting effect on the individual in terms of later educational and achievement outcomes. Australian Journal of Education, Vol. 50, No. 2, 2006, 122–139 122