James Thomson was born in Ednam in Roxburghshire around 11th September 1700 and baptised on 15th September. He was the fourth of nine children to father Thomas, the Presbyterian minister of Ednam and mother Beatrix.

Apart from the exact date of his birth several other facts of his life cannot be verified.

It is thought Thomson may have attended the parish school of Southdean, his father having been appointed minster there a few months after the birth of his son, before attending the grammar school in Jedburgh in 1712. Accounts of his early abilities are almost always negative. Poetry however was his great love. In this he was encouraged by Robert Riccaltoun, a farmer, poet and Presbyterian minister; and Sir William Bennet, a whig laird who was also the patron of Allan Ramsay. Very few early poems by Thomson survive. It seems that on each New Year’s Day he burned almost all of his year’s output.