On 14 Apr 1803 when Francis was 27, he married Elizabeth Ruggles (52307) , daughter of William Ruggles (39301) (30 Apr 1733-18 Mar 1788) & Abigail Walker (35484) (27 May 1741-17 Oct 1801), in Billerica, MA. Born on 29 Apr 1778 in Leominster, MA. Elizabeth died in Billerica, MA, on 13 Oct 1834; she was 56.

Children of Francis and Elizabeth (Ruggles) Cook, born at Billerica:
    i. Betsey Cook, b. 30 Mar 1804;
    ii. Francis Cook, b. 3 Apr 1805;
    iii. Sears Cook, b. 1 May 1807;
    iv. Francis Cook, b. 14 Aug 1808;
    v. John Cook, b. 24 Mar 1811; and
    vi. William Cook, b. 23 Feb 1817.

Susannah first married Benjamin Walker (45130) , son of Timothy Walker Esq. (35480) (5 Jul 1732-9 May 1809) & Eunice Brewster (25860) (12 Mar 1731-2 Jun 1815). Born on 3 Jul 1767 in Wilmington, MA. Benjamin died in Wilmington, MA, on 26 Jun 1811; he was 43. Buried in Wildwood Cemetery, Wilmington.

On 30 Nov 1815 when Susannah was 37, she second married Ezra Kendall in Wilmington, MA.