The risk of bullying, self-harm, injury and early drop-out by recruits at armed forces' training centres is "too high", an independent report says.
The report was triggered by the deaths of four recruits at Deepcut
The Adult Learning Inspectorate urged training to be "better managed, better organised and better controlled".
The report - commissioned after four soldiers died at Deepcut Barracks - is the second in a week to criticise bullying in the Army, Navy and RAF.
Armed Forces minister Adam Ingram said both reports would be acted upon.
The Commons Defence Select Committee reached similar conclusions in its report published a week ago, accusing the Army of failing in its handling of bullying.
Adult Learning said the armed forces' own data showed about one in 10 military personnel - or 20,000 across the three services - suffered bullying or harassment.
"Much of this is condoned as 'traditional', even though it is officially forbidden," it said.
"The newest recruits, women and people from minority ethnic groups are particularly vulnerable."
Mr Ingram had asked the inspectorate to investigate, following a report by Surrey Police into the deaths of the four young recruits at Deepcut Barracks in Surrey between 1995 and 2002.
James Collinson, 17, from Perth, Geoff Gray, 17, from Seaham in County Durham, Sean Benton, 20, from Hastings in East Sussex, and Cheryl James, 18, from Llangollen in north Wales, all died from gunshot wounds in unexplained incidents at the base.
Mr Adam Ingram welcomed the latest report as an "independent and wide-ranging" review of training.
He said: "We will use this information to raise the standards of all defence training establishments."
Vice Chief of the Defence Staff, Air Chief Marshall Sir Anthony Bagnall said: "The report highlights that we can do more to better manage the inevitable risks of such training.
"In particular, we are determined none of our young men and women should endure bullying or harassment of any nature during their tough training regime."
The families are still pushing for a full public inquiry into the deaths.
Geoff Gray's father, also called Geoff, said on Monday: "I realise the regime has to be tough but it's got to be civilised."
The inspectorate interviewed 4,700 trainees and 2,000 staff, and analysed 450 questionnaires returned by families of recruits.
It said some lessons had been learnt after Deepcut, but good practice was still limited.
It added: "The armed services have much to be proud of, but the risks to young recruits are too high."
It said a high early drop-out rate was frequently dismissed as inevitable, but was actually costly to the forces and distressing to those involved.
Other concerns were that training and welfare should be more professionally managed, that some living conditions were "little better than slums" - and that storage of weapons could be lax.