The signature on land deeds show that Thomas' wife's name was Mary. That her maiden name was Lincoln does not seem to be documented except on a Family Pedigree Chart of unknown origin.

Family tradition says that Thomas Caswell came from Somersetshire, England, in 1640. In the parish of north Curry in Somersetshire, there is a record that one Thomas Caswell was baptized there on 20 October 1618, son of Thomas Caswell. If this is our Thomas, it would make him about 22 years old when he emigrated, not an unreasonable assumption.

In Taunton, in August of 1643, his name first appears as "Thom Caswell" on a list of "males 16 to 60 able to bear arms." Although not among the original proprietors of Taunton, he was an early settler there and did become a proprietor and as such took part in the South and North Purchases.

In 1657, "Tho: Casswell" took the oath of fidelity in Taunton. He served on several panels and committees which gives an indication of his good standing in the community. Starting with very little, Thomas acquired through grants and purchases several tracts of land totaling several hundred acres. His will and inventory show his land holdings to be sufficient to set up his sons and sons-in-las on farms of their own. His will was signed 28 September 1691 and was probated 14 September 1697.

Thomas and his wife Mary (Lincoln) Caswell had twelve children, all born in Taunton, MA:

• Stephen, b. 15 Feb. 1648/9; m. Hannah Thrasher, sister of Israel Thrasher.
• Thomas, b. 22 Feb. 1650/1.
• Peter, b. 31 Oct. 1652.
• Mary, b. 31 Aug. 1654; m. Israel Thrasher.
• John, b. 31 July 1656.
• Sarah, b. 3 Nov. 1658; m. William Hoskins.
• William, b. 15 Sept. 1660.
• Hannah, b. 14 July 1661; named in Thomas' will; m. Daniel Ramsdell.
• Samuel, b. 26 Jan. 1662/3.
• Elizabeth, b. 10 Jan. 1664/5; m. Uriah Leonard.
• Abigail, b. 27 Oct. 1666; m. Joseph Jones.
• Esther, b. 4 June 1669; m. Samuel Smith.