On 29 Dec 1766 when Isaac was 24, he first married Mary Mansfield (54415) , daughter of Lieut. Nathan Mansfield (15 Nov 1718-13 Mar 1783) & Deborah Dayton (38222) (8 Aug 1724-29 May 1817), in Second Congregational Society, New Haven.55 Born on 14 Dec 1745 in New Haven, CT.56 Mary was baptized in New Haven, CT, 18 Feb 1748/9.634 Mary died in New Haven, CT, on 16 Aug 1805; she was 59.55 Buried in City Burial Ground, New Haven.

Dr. Stiles, writing in 1793, stated that “Mrs. Beers is of a singularly tenacious and retentive memory, well read, an excellent historian and versed in family anecdotes and antiquities of New Haven. ... Mrs. Beers was a born historic genius.”6

Children of Isaac and Mary (Mansfield) Beers, baptized in New Haven:
    i. Sally Maria, bp. 12 Feb 1786, d. 25 Aug 1839 at New Haven, m. William C. Leffingwell (b. Sep 1765 at Norwich, CT, d. 23 Oct 1834 at New Haven); and
    ii. Elizabeth, bp. 12 Feb 1786, d. 24 Jul 1820, m. Joseph Lucius Wooster.488

Isaac second married Sarah Gorham (48782) , daughter of John Gorham (31411) (ca 1726-bef 18 Jul 1768) & Lydia Dorman (40082) (12 Mar 1726/7-9 Jan 1782). Born in New Haven, CT. Sarah died in New Haven, CT on 16 Dec 1837.

Sarah, widow of Woodbridge Townsend, married second Isaac Beers as his second wife.