The government has denied claims the British armed forces are glamorising war to boost recruitment.
The Joseph Rowntree Charitable Trust says recruits are unable to make informed choices about enlisting and children are being targeted.
It also suggests many young recruits leave when they discover the reality of life in the military.
But the Ministry of Defence says many of the claims are "out of date, incorrect and ill-informed".
The report's author, David Gee, told the BBC that new recruits cannot predict how they will feel later on in their lives.
"I think young people are particularly vulnerable to the pressures of an Armed Forces career.
"They can't know what they'll want at age 20 when they're 16. At the moment there is no effort to introduce the downside of Armed Forces life.
"I'm not saying their recruitment literature needs to show the full horrors of war. But I think they need to reflect a more balanced picture."
The Joseph Rowntree Charitable Trust is a Quaker organisation which is "committed to a culture of peace and the creation of a peaceful world".
Quakerism holds pacifism as a cornerstone of its religious beliefs.
The report - Informed Choice? Armed Forces and Recruitment Practice in the UK - makes a number of claims, including how for every two 16-to-22 year olds joining the army, one is leaving.
It also states that in 2007, a survey found 48% of all soldiers found army life to be worse than expected, with only 20% thinking it was better.
The report also says many recruits enlist without fully understanding their legal obligations and that recruitment literature fails to mention how, unless they leave within six months of enlisting, minors have no legal right to leave for four years.
The trust's report recommends sweeping changes to recruitment policies, including a new charter setting out the state's responsibilities, a radical review of recruitment literature, phasing out recruitment of minors and new rights for recruits to leave service.
A new website, Before You Sign Up, also funded by the trust, has been launched that claims to give "independent and fair information about the benefits, risks and terms of service of a career in the armed forces".
Armed Forces Minister Bob Ainsworth said armed forces recruitment needed to be based on truth to ensure that the military personnel were fully motivated.
"I think we are truthful for two main reasons. One is that we have a moral obligation to be so but the other one is that it's not in our interests to paint a distorted picture.
"We do not want people joining the armed forces who are not motivated, who are not capable of undertaking the training that we want them to undertake and doing the job that we ask of them at the end of the day.
"We try to be factual and we try to give them a rounded picture."
Barry Donnan was in the Army for six years and served in the first Gulf War, and thinks more should be done to highlight the life-threatening dangers that new recruits could face.
He said: "Why isn't that practical to be truthful to people and let people know?
"The report here is particularly highlighting the case of vulnerable people who are going through the system at maybe 15, 16 years old, 17, 18 who I would suggest are not mature at that age.
"I was 16 years old when I went through it. At 16 you can't join the police, can't drink alcohol, can't vote yet you can join up [to the armed forces]."
An MoD spokeswoman refuted many of the trust's claims, saying the armed forces did not target those under 16.