Channel 4 said the ruling vindicated its welfare considerations
Channel 4 documentary Boys and Girls Alone fell foul of broadcasting watchdog Ofcom's code of conduct, the organisation has concluded.
The four-part programme's first episode failed to give enough information on how its young participants were being looked after, it said.
It noted the children, who were shown living unsupervised, had had their welfare safeguarded throughout filming.
The series, shown earlier this year, prompted a number of complaints.
Viewers and child welfare organisations expressed concerns about the programme, which monitored the children's efforts to live without adults.
Ofcom, which received 180 complaints about the show, said the opening episode's narrative was "insufficient to reassure viewers about their welfare, given the editorial purpose of the series and the specific context of episode one".
It warned the broadcaster that it did not do enough to ensure viewers were "adequately protected from potentially offensive material".
But it added that safeguards put in place by Channel 4, including parental monitoring and selection procedures, were "numerous and comprehensive".
While some parts of the serial showed the children in a state of upset, it ruled that "in reality, the likely risks for the children were in most cases negligible".
Channel 4's head of programming Julian Bellamy welcomed Ofcom's ruling and said: "Channel 4 takes its responsibilities towards the welfare of children in its programming extremely seriously.
He added that he is "extremely pleased" that the programme maker's "careful consideration and preparation" has been vindicated by Ofcom.
Mr Bellamy said they noted the recommendation to be "mindful of viewers' sensitivities of viewers with regard to factual programming of this nature involving children".