John Adams didn't attend the Constitutional Convention because he was serving as ambassador to England. He sent letters in support of the Convention. John Adams was named the first United States minister to Great Britain in 1785. He served in that capacity until 1788. Prior to that, he had been in Europe trying to negotiate trade treaties with Great Britain, the Netherlands, and France, and took part in the peace treaty negotiations with Great Britain, ending the Revolutionary War. He served his nation in Europe for almost ten years, from 1778 until 1788.
did not attend the constitutionthomas Jefferson, Patrick Henry, john Adams, thomas Paine, and several more! (Charles Townshend)The answer above is correct but could be improved by adding that the State of Rhode Island did not attend the Constitutional Convention because IRS leaders opposed a stronger central government.
John Adams, Patrick Henry, and Thomas Jefferson were a few of the important Founding Fathers who weren't present at the Constitutional Convention. John Adams and Thomas Jefferson were overseas, and Patrick Henry refused to attend because he "smelt a rat" and didn't trust the intentions of his fellow delegates.