Leonard Dalton Abbott (1878–1953) was an English-born American publicist, politician, and freethinker. Originally a socialist, Abbott turned to anarchism and remained a Georgist later in life. He is best remembered as a leader of the so-called "Modern School movement" of those years.
Leonard D. Abbott was born in Liverpool, Lancashire, England on May 20, 1878. Leonard's father, Lewis Lowe Abbott, was a prosperous New England metal merchant of Anglo-Saxon ethnic stock and a graduate of Yale College. In January 1876, the elder Abbott took a position with the firm of Dickerson & Co. and on behalf of that firm spent the next two decades in Liverpool representing the commercial interests of American firms abroad. It was owing to this employment situation that Leonard, the child of American parents, was born abroad. Abbott's siblings included Clinton Gilbert Abbott (1881–1946), who became director of the San Diego Natural History Museum.
Leonard came to the United States for the first time in 1897, settling in New York City. Under the influence of the British socialist-turned-anarchist William Morris, Abbott engrossed himself in the socialist movement, in which he remained an active worker up to 1905.
Shortly after his arrival in America, Abbott became the art editor for The Literary Digest, one of the leading news weeklies of the period. Abbott also reported on the American socialist movement to the British Labour Annual each year from 1899 to 1901.
Abbott was a leading figure in the Social Democratic Party of America (SDP), an organization based in Chicago and headed by journalist Victor L. Berger and union activist Eugene V. Debs. He was a keynote speaker at a June 1900 convention which united the forces of the Chicago SDP and an organization formerly hailing from the Socialist Labor Party of America behind the Presidential candidacy of Eugene Debs and Benjamin Hanford. Abbott was named a candidate of the combined Social Democratic Party for New York State Treasurer by that same gathering.