Staffordshire Children's Services rated 'poor'
Staffordshire's Children's Services is performing "poorly" overall, according to national watchdog Ofsted.
Inspectors said "significant delays" in sharing welfare concerns, and deciding what action to take, could mean some children experience further harm.
Last year, Ofsted said the county council department was performing well.
Councillor Mike Lawrence said the authority had failed in one area - child protection - but had improved in many others.
Mr Lawrence, cabinet member for children's wellbeing, said: "The adoption, the fostering service, our children's zones, our children's centres, disability respite unit are all good or outstanding.
"It's just this one area where we were given a priority action and it is that priority action which has caused us to be given a performing poorly."
Ofsted said the local authority's child protection system met statutory requirements in several areas, but added: "Nevertheless, there are serious weaknesses in important aspects of provision."
The assessment follows an unannounced two-day inspection in June.
Mr Lawrence said: "There were no surprises from the Ofsted inspection back in June. We were aware of the issues they had identified and we were in the process of putting them right."
Inspectors praised most early years and nursery providers in the county, along with the performance of "a large majority" of primary and secondary schools.
Ofsted said there had been further improvement in council-run special schools, seven of which were "outstanding".
It said the reorganisation of secondary schools, including the launch of six academies, had resulted in an improvement on last year.
It added that three of the academies had been classified as "outstanding".
However, Ofsted also said there had been little year-on-year improvement among early years providers and primary schools.
The watchdog also reported that the gap between 16 year olds from low income families and students of the same age from other backgrounds had widened over the last two years and was greater than the national average.
It also criticised post-16 education in Staffordshire, saying two thirds of providers were "no better than satisfactory," with very little change since last year.