Josiah Coolidge was born 17 July 1718 in Watertown, Middlesex County, Massachusetts to Obadiah Coolidge (1695-1741) and Rachel Goddard (1699-1740) and died 25 December 1780 Lancaster, Worcester County, Massachusetts of unspecified causes. He married Mary Jones (1720-1756) 26 April 1742 in Brookline, Norfolk County, Massachusetts.
Children
| Name | Birth | Death | Joined with |
| Mary Coolidge (1741-) | |||
| Josiah Coolidge (1750-) | |||
| John Coolidge (1756-1822) | 1756 Bolton, Worcester County, Massachusetts, United States | 23 March 1822 Plymouth, Windsor County, Vermont, United States | Hannah Priest (1750-1828) |
| Obadiah Coolidge (1760-1822) | |||
| Isaac Coolidge (1761-) | |||
Siblings
| Name | Birth | Death | Joined with |
| Josiah Coolidge (1718-1780) | 17 July 1718 Watertown, Middlesex County, Massachusetts | 25 December 1780 Lancaster, Worcester County, Massachusetts | Mary Jones (1720-1756) |
| Hannah Coolidge (1720-) | |||
| Lydia Coolidge (1723-) | |||
| Obadiah Coolidge (1728-1767) | |||
| Isaiah Coolidge (1733-1772) | |||
| Rachel Coolidge (1737-1766) | |||