The report from London University's Institute of Education found that most students from General National Vocational Qualification (GNVQ) courses went into jobs unrelated to the subjects they had studied.
A high proportion of young people work in retailing or in hospitality and catering but very few choose relevant GNVQs.
Over three-quarters of students are concentrated in four subjects, art and design, business, leisure and tourism, and health and social care. The report questions whether that was what the last Government's meant when it said that they should be "a broad preparation for employment."
Professor Alison Wolf, who carried out the project, said the courses "represent a very small proportion of the country's occupational map". Technical jobs are poorly represented.
The qualifications have also failed to achieve equal standing with A- levels - another objective. That is partly because old vocational qualifications persist so that the new courses have not become the main alternative to A-levels. Only a fifth of 16-year-olds takes them compared with the target of a quarter for 1996.