The Secret Six were Thomas Wentworth Higginson, Samuel Gridley Howe, Theodore Parker, Franklin Benjamin Sanborn, Gerrit Smith, and George Luther Stearns. All six had been involved in the abolitionist cause prior to their meeting John Brown, and had gradually become convinced that slavery would not die a peaceful death.

Of these six men, only Smith and Stearns were truly "wealthy"; the others consisted of two Unitarian ministers (Parker and Higginson) a doctor (Howe), at a time when men of medicine were "middle class", and a teacher (Sanborn). Gerrit Smith later bailed Jefferson Davis after the Civil War.