John Bartlett was born in Concord, Massachusetts in 1784 as the fourth of twelve children and as a youth was greatly influenced by his local pastor, Dr. Ripley.
After working with a relative in commerce in Maine, Bartlett returned to Massachusetts and graduated from Harvard College in 1805.
Bartlett also studied medicine, although he never intended to be practicing physician, but thought the education useful in his work with the impoverished.
After observing the conditions of the poor at the Almshouse, Bartlett visited the hospitals in New York and Philadelphia and researched the newest medical methods.
In 1811 Bartlett was ordained as pastor of the Second Congregational Church in Marblehead, Massachusetts, where he held to a Unitarian theology.