On 28 Dec 1709 when Josiah was 23, he married Mary Marston (10772) , daughter of James Marston (3587) (19 Nov 1656-3 Sep 1693) & Dinah Sanborn, in Hampton, Rockingham County, New Hampshire.40 Born on 22 Nov 1687 in Hampton, Rockingham County, New Hampshire.40 Mary died in Hampton, Rockingham County, New Hampshire, on 12 Sep 1774; she was 86.40

Josiah and Mary were second cousins. His maternal grandfather and her paternal grandfather were brothers.