TLG polled 1,000 parents and found that 23 per cent were most concerned about whether their child's making the right progress, while more than half (52 per cent) placed it in their top three concerns.
One in five were most concerned about their child being bullied, while more than one in ten were most concerned about their child feeling unhappy at school. One in ten were most worried about their child being exposed to inappropriate language, conduct or material.
The concerns coincide with a decline in the overall proportion of children achieving A* to C in their GCSEs, dropping from 69% to 67% in 2016, and an increase in school exclusions.
Speaking on Premier's News Hour Tim Morfin, chief executive of TLG called for churches to do more to support parents who are concerned about their child's progress at school.
He said: "There is a group of children for whom the resources of the local school are not yet available for them and actually there is a great space in which the local church can make a real difference.
"In our Early Intervention Centres we've got 65 churches across the country providing volunteer coaches for kids in school and those schools are delighted to have that partnership with the local church.
"The local church can be the place where families can receive that support and that encouragement that we all need as parents."
Listen to Premier's Marcus Jones speaking to Tim Morfin on the News Hour: