Jonathan married Hannah Peabody (21421) , daughter of William Peabody (7966) (3 Mar 1646-6 Mar 1699/1700) & Hannah Hale (11279) (19 Nov 1663-23 Feb 1732/3). Born ca 1693 in Boxford, MA. Hannah was baptized in Topsfield, MA, on 6 Aug 1693. Hannah died on 1 Jun 1769.

Children of Joanthan and Hannah (Peabody) Foster:
    i. Oliver Foster, b. 17 Aug 1719 at Boxford;
    ii. Hannah Foster, b. 15 Dec 1721 at Boxford;
    iii. Jonathan Foster, b. 11 Oct 1727 at Haverhill;
    iv. William Foster, b. 9 Nov 1729 at Haverhill; and
    v. Richard Foster, b. 20 Feb 1732/3 at Boxford.