The stocktake, which launched in April and is being carried out by longstanding government adviser Sir Martin Narey and children' social worker Mark Owers, aims to build a comprehensive picture of what foster care looks like and how it can be improved.
It is due to conclude in December and has involved calls for evidence from social workers, foster carers, academics, councillors, parents and young people.
But at an education select committee hearing, in which young people with experience of care sat alongside MPs, children's minister Robert Goodwill was told that the stocktake was failing to properly engage young people.
Among those questioning Goodwill was Luke Rodgers, a care leaver and founder of Foster Focus, an organisation that works with councils to improve quality of care and youth participation. Rodgers said youth participation in the stocktake had been too limited, mainly focused around an eight-question survey that young people were required to complete by last month.
"In terms of how we involve young people in the stocktake, which is for them, it has been diabolical if I'm honest, and we need to be involving young people more in these things to get their opinions," said Rodgers.
"We need to provide a more diverse platform for them, not just a questionnaire or a couple of people on social media."
He added: "I don't think the consultation with young people on the fostering stocktake has been good enough."
Latest DfE figures show that, as of 31 March 2017, there were 53,420 children in foster placements.
Connor Richardson, another young person with experience of care at the hearing, urged the government to create a far broader, national survey for young people to submit their views.
"One thought I've had is if the government could set up a national survey for young people in the care system to get their views directly. If they have any ideas or thoughts to put across they can do that within that survey," he said.
Committee chair Robert Halfon asked Goodwill for his views on "making sure that more younger people are involved in the stocktake".
Goodwill said: "We have a general problem in society that young people don't necessarily get engaged."
He added that he hoped that "when we do publish the stocktake that through social media and all the other ways they communicate that they will be feeding their thoughts through".
Also appearing at the hearing was the Department for Education's director of children's social care, practice and workforce Katy Willison, who defended the way the stocktake had engaged with young people.
"It's a fair challenge," she said.
"The stocktake does need to consult with as many young people as possible. One of the things Sir Martin Narey has told us is that he has heard a lot of children's voices through social media and Twitter so he is genuinely trying to gather voices from lots of different platforms."
She added: "He (Narey) is genuinely trying to engage in that way and through meeting and talking to people. We hope he gets as much as he can from that."
