Members are to hold a further inquiry to explore the "balance between supporting families and intervening to remove children from harmful situations".
School attendance rates were lowest for children looked after at home (78.7 per cent); those for children looked after by foster carers are "very high", at 96 per cent.
MSPs were "very concerned" by comments by directors of education and social work that there had not been enough attention paid to the needs of looked-after children who stayed at home.
They heard what they described as "often disturbing evidence" about the consequences for children if they did not have sustainable, loving, secure and stable relationships with parents or carers from a very early age and called for the government's national parenting strategy to be "properly resourced" in light of their findings.
The committee nevertheless acknowledged that "considerable efforts" had been made since devolution to narrow the attainment gap.
Factors which could improve the situation include: fewer "informal exclusions" from school that lead to part-time education; better early intervention; more stable placements; and better relationships between the various professionals dealing with looked-after children.
The report also calls for "greater efforts" to establish "corporate parenting" approaches among all school staff, and training for teachers in issues around attachment theory, nurturing, and the needs of looked-after children.
MSPs said there was "clear consensus among witnesses that the use of part- time education, where no other provision is put in place, is unsatisfactory, as every child has a right to a full-time education".
The committee welcomed Curriculum for Excellence's recognition of wider achievement, but called on the Scottish government to introduce monitoring and reporting of wider achievement at a national level.