On 9 May 1767 when Joshua was 24, he married Mary Flagg (34801) , daughter of Bezaleel Flagg (16607) (23 Mar 1710/1-21 Jan 1749) & Sarah Bemis (37936) (11 Nov 1711-).30 Born 14 Jan 1747/8 in Waltham, MA.30

Children of Joshua and Mary (Flagg) Peirce, the first two born at Waltham, the others at Weston:
    i. Jacob Peirce, b. 23 Jul 1767;
    ii. Sarah Peirce, b. 18 Sep 1769;
    iii. Eunice Peirce, b. 28 Oct 1771;
    iv. Nahum Peirce, b. 7 Feb 1774;
    v. Polly Peirce, b. 2 Jul 1776;
    vi. Abigail Peirce, b. 1 Nov 1778;
    vii. Ichabod Peirce, b. 3 May 1781;
    viii. Lydia Peirce, b. 11 Dec 1783;
    ix. Joel Peirce, b. 28 Dec 1785; and
    x. Grace Peirce, b. 18 Jun 1790.30