The findings suggest that there may be no significant difference between the achievement of first-, only-, and last-born children. While middle-born children appeared to do less well in academic achievement, their occupational achievement did not differ significantly from the other birth-order groups. The findings suggest further that sibling-identification may affect the occupational achievement of last-born offspring, while parental activity appears to influence the academic and occupational achievement of first- and only-born children. Last-born offspring appear to do better in occupations predominated by co-workers of the same sex as their next-older sib. For the Last-Born in an occupation predominated by co-workers of the opposite sex of his next-older sib, occupational achievement correlated positively with an increase in the age space between the Last-Born and his next-older sib. (Author)