During the early 1920s, Caroline Lloyd and her daughter Estelle, members of a family who controlled an oil field in Ventura County, California, began sending a large portion of their income to Hall.

[3]: 41  While visiting London in the early 1930s, Hall acquired from an auction agent at Sotheby's a substantial collection of rare books and manuscripts about alchemy and esotericism.

He utilized print and word-of-mouth advertising to solicit public funding to finance his book The Secret Teachings of All Ages (1928), and hired John Augustus Knapp to create full color illustrations, and black and white drawings.

"[5]: 20  As one writer put it: "The result was a gorgeous, dreamlike book of mysterious symbols, concise essays and colorful renderings of mythical beasts rising out of the sea, and angelic beings with lions' heads presiding over somber initiation rites in torch-lit temples of ancestral civilizations that had mastered latent powers beyond the reach of modern man.

"[6]: 4 After the success of The Secret Teachings of All Ages Hall went on to publish several books, the major of which included, The Dionysian Artificers (1936), Freemasonry of the Ancient Egyptians (1937), and Masonic Orders of Fraternity (1950).

Continuing his career into his seventies and beyond, Hall delivered approximately 8,000 lectures in the United States and abroad, authored over 150 books and essays, and wrote countless magazine articles.

[8] President Ronald Reagan is reported to have adopted ideas and phrasing from The Secret Destiny of America (1944) in his speeches and essays for his allegorical use of the City upon a Hill.

[7][8] Historian Mitch Horowitz has brought attention specifically to Reagan telling the story of an "unknown speaker" at the signing of the Declaration of Independence and America’s assignation "to fulfill a mission to advance man a further step in his climb from the swamps.

[3]: 120, 127, 133, 278 In 1934, Hall founded the Philosophical Research Society (PRS) in Los Angeles, California, a nonprofit organization[11] dedicated to the study of religion, mythology, metaphysics, and the occult.

[18] On 8 December 1973 (45 years after writing The Secret Teachings of All Ages), Hall was recognized as a 33° Mason (the second highest honor conferred by the Supreme Council of the Scottish Rite) at a ceremony held at the Philosophical Research Society (PRS).