The function of the committees was to alert the residents of a given colony of the actions taken by the British Crown, and to disseminate information from cities to the countryside. The news was typically spread via hand-written letters or printed pamphlets, which would be carried by couriers on horseback or aboard ships. The committees were responsible for ensuring that this news accurately reflected the views, and was dispatched to the proper receiving groups. Many correspondents were members of colonial legislative assemblies, and others were also active in the Sons of Liberty and Stamp Act Congress.
A total of about 7,000 to 8,000 Patriots served on these committees at the colonial and local levels, comprising most of the leadership in their communities; Loyalists were naturally excluded. The committees became the leaders of the American resistance to Great Britain, and largely determined the war effort at the state and local level. When Congress decided to boycott British products, the colonial and local committees took charge, examining merchant records and publishing the names of merchants who attempted to defy the boycott.
The committees promoted patriotism and home manufacturing, advising Americans to avoid luxuries, and lead a more simple life. The committees gradually extended their power over many aspects of American public life. They set up espionage networks to identify disloyal elements, displaced royal officials, and helped diminish the influence of the British government in each of the colonies.