The Government is being urged to do more to raise awareness of apprenticeships to boost the country's productivity.
The National Audit Office said the Department for Education had not set out how it would use the increase in apprentice numbers to improve productivity.
The department was urged to set out how it measured apprenticeships as being successful.
Amyas Morse, head of the National Audit Office, said: "The Department for Education needs to chart and follow a course from having a lot of apprenticeships to having the right apprenticeships in order to help improve the UK's productivity, and achieve value for money, in return for the costs of the programme."
Apprenticeships and Skills Minister Robert Halfon said: "Our apprenticeship reforms give young people a ladder of opportunity, provide employers with high quality apprentices and deliver real benefits to the economy.
"We are giving employers more power than ever before to design apprenticeships that are rigorous, robust and world class.
"The new Institute for Apprenticeships will ensure that apprenticeships are even more closely tailored to the needs of employers."
Public and Commercial Services union general secretary Mark Serwotka said: "While the number of apprentices continues to rise the Government has no clear plan for ensuring they are being used effectively and not exploited as cheap labour by unscrupulous employers."