Harris is best remembered as the leader of a series of communal religious experiments, culminating with a group called the Brotherhood of the New Life in Santa Rosa, California.

J. L. Scott he launched the first of his communal enterprises, the Mountain Cove Community of Spiritualists, on pristine land claimed by one of the group's leaders to be the actual site of the Garden of Eden.

[3] Following the collapse of the Mountain Cove Community, Harris went back to his native England, where he preached modified Swedenborgian ideas to a London congregation for several years.

[3] He would remain at Amenia for five or six years, establishing a bank, a flour mill, and a vineyard, and gathering around him a small group of devoted religious disciples.

Its nature was co-operative rather than communistic, and farming and industrial occupations were engaged in by his followers, numbering at one time about 2,000 in the United States and Great Britain.

For a time in 1876 Harris discontinued public activities, but issued, to a secret circle, books of verse dwelling mainly on sexual questions.

About 1881, Laurence Oliphant and his wife broke away from the sect, charging Harris with robbery and succeeding in getting back from him many thousands of pounds by legal proceedings.

But in the end he came to practice unbridled licence under the loftiest pretensions, made the profession of extreme disinterestedness a cloak to conceal his avarice, and demanded from his followers a blind and supple obedience.

These included: Harris's community left a significant stamp on the history of Santa Rosa; today that part of town is still called Fountaingrove.

The round barn that was part of the winery of Harris's protege, Kanaye Nagasawa, was an emblem of the community; it burned in the 2017 Tubbs Fire.

He depicted interplanetary empires, imperial cities entirely covering planets, and the "ancient astronaut" myth, in which space travellers help early humans with agriculture, technology and spiritual development.