A report published by the Office for Standards in Education yesterday reveals big variations in schools' readiness for the subject, which will be statutory from September for pupils aged 11 to 16.
Inspectors examined a sample of 20 secondary schools and found that more than half had made good preparation. But at least a third still had a considerable amount to do, and two were ill-prepared.
The report states that most schools need to give more thought to the "participation and responsible action" strand of citizenship and that some mistakenly believe they already cover it.
"In a few schools there appeared to be some degree of complacency, believing that all of the ingredients were 'covered', but without having given due thought to the depth or quality of coverage," it says.
The inspectors found that the schools which had adopted the most "minimal" approach were often those where teachers had a negative attitude towards citizenship and complained of over-crowding in the curriculum.
OFSTED urges schools which plan to teach citizenship in personal, social and health education classes to check that there is enough time.
"Citizenship: Preparation for the introduction of citizenship in secondary schools"; www.ofsted.gov.uk