The Texas school board has adopted a resolution urging publishers to keep "pro-Islamic/anti-Christian" language out of textbooks in the state.
Among other complaints, the non-binding decree says some textbooks devote more lines to Islam than to Christianity and print "whitewashes" of Islamic culture.
Critics say it relies on a flawed reading of books that are out of use.
In May, the panel adopted guidelines that critics said injected conservative political ideas into the curriculum.
Texas is one of the largest textbook markets in the US, and a vote in favour of the resolution could carry considerable weight in the publishing industry, supporters say.
In a 7-6 vote, the Texas School Board adopted the resolution calling on textbook publishers to limit what they print about Islam, the world's fastest growing religion.
The resolution is nonbinding on future boards, which will choose the state's next generation of social studies texts.Warning to publishers
The resolution comes at a time of growing anti-Islamic sentiment in the US, with Mosque building projects across the country being challenged and a growing number of Muslims complaining of workplace harassment.Supporters say the resolution is needed to warn textbook publishers not to print "anti-Christian" books if they want to sell them to Texas schools. It says in the board "will look to reject future prejudicial social studies submissions."
The measure was drafted by Randy Rives, a businessman and former school official in the Texas city of Odessa. It was introduced by a bloc of social conservatives who currently control the board.
"It's the pro-Islamic, anti-Christian teachings in these books, that is what we are concerned about," Mr Rives told the BBC.
"We're teaching double the beliefs and specifics about another religion than we are about Christianity, which is the foundation of our country."
Among several complaints, the resolution says that a textbook used until 2003 used pejorative language to describe the crusaders while "euphemising Muslim conquest of Christian lands as 'migrations'".
It also says a book approved for use in Texas schools until 2003 devoted 159 lines of text to Islam and only 82 to Christianity, and recounted crusaders' massacres of European Jews while ignoring a 15th Century massacre of Baghdad Muslims by the Muslim conqueror Tamerlane.Flawed reading
Mr Rives, a Republican who lost an election for the state school board this year, rejected criticism the resolution refers to books no longer used in Texas schools.
"The big concern is that we don't let it happen in the future," he said.
The Texas Freedom Network, an organisation that says it promotes religious freedom and individual liberties and opposes "the religious right", accused the Texas board of manufacturing controversy instead of focusing on education. It said the resolution relied on a flawed reading of textbooks that overlooked certain passages.
"This resolution is another example of state board members putting politics ahead of expertise and refusing to consider the advice of real scholars before doing something provocative and divisive," the group said in a statement.
"Indeed, the board has asked no scholars or other experts for public advice about the resolution."