Big August Quarterly is an annual religious festival held in Wilmington, Delaware (sometimes called "Big Quarterly" or "August Quarterly"). Begun in 1814 by Peter Spencer in connection with the "quarterly" meeting (or "conference") of the African Union Church -- of the four meetings during the year, the one in August became the "annual conference" of the Church when ministers' assignments for the next year were announced, among other business -- it was a time for free blacks and slaves alike to come together (from the multi-state area) and celebrate their faith with singing, dancing, testifying, and feasting. It is the oldest such celebration in the country.

Delaware's Senator Joe Biden's remarks on the significance of the "Big Quarterly" were published in the Congressional Record for 30 July 1981 (Vol. 127, No. 117) and for 9 August 1984 (Vol 130, No. 106).