Summary.The Rothwell Miller Interest Blank was completed by members of the National Survey of Health and Development, two months before their fifteenth birthday. Their scores on this inventory were subjected to a component analysis. Interpretations of the first three components are made by examining the job choices of the Survey members. The first component ‘ambition’ is related to home and school factors. It is shown that the social composition of the school is an important determinant of ambition at nonselective scho