Entries for summer 2007 are running at about 80,000, compared with 54,000 last year. Citizenship was introduced as a GCSE course in 2002.
Tony Breslin, chief executive of the Citizenship Foundation, said that the number of entries had increased because more schools were teaching citizenship as a separate subject at key stage 4 and wanted pupils to gain a qualification at the end of the course.
This demand for qualifications in the subject is reflected in plans for new exams. From next year, students will be able to take an A-level in citizenship, and from 2009 a full GCSE course will be on offer.
Mr Breslin said that these changes meant teachers and schools were beginning to take citizenship seriously.