The inspection agency Estyn said management of the authority's young people's partnership suffered from a lack of strategic leadership because many senior managers do not attend regular meetings, and the different services that make up the partnership do not communicate well.
In a recent survey, nearly one quarter of staff said they did not know how their work contributed to the work of the partnership.
Estyn's report acknowledged that much of the provision was of a good quality, but said there was a high risk of losing funding for some services because of poor planning. Blaenau's young people's partnership, known as the youth entitlement partnership (YEP), supports the services for 11 to 25-year-olds.
Estyn's inspectors found that most young people who take part in youth services gain new knowledge and skills. Staff establish good working relationships with young people, in some cases agreeing a behaviour contract.
There is a good range of support, advice and guidance for young people across the borough, said the report. The partnership provides good support for disadvantaged groups in one of the most socially deprived authorities in Wales.
The report cites the success of specific schemes such as Catapult, which works informally with 16 to 25-year-olds on accredited and non-accredited courses, and Talk It Up, a borough-wide forum for young people.
There was also a fitness programme aimed at young men involved in anti-social behaviour and the C-Card scheme, where young people can use their mobile phones to ask for sexual health advice.
But Estyn said the service's staff do not always plan their work well and do not provide enough opportunities for young people to develop basic and ICT skills. They also do not include bilingualism in their work.
"There is no centrally-based counselling service, not enough open access information services, and not enough work with young men over 16," stated the report.
In a statement, the partnership said it recognised many of the shortcomings identified by Estyn.
But it added: "The report supports the partnership findings that there is a high level of good-quality youth support service here in Blaenau Gwent."