While in the Congress, Tilghman debated and supported the Declaration of Independence. He voted for its final approval, but was replaced in the Congress by Charles Carroll of Carrollton before a copy was signed. Matthew had to return home to preside over a longer session of the Annapolis Convention that established a new government for Maryland. Besides being President of the Convention, he headed the Committee that drafted the "Charter of Rights and Plan of Government" that was Maryland's first constitution.