Roerichism or Rerikhism (Russian: Рерихи́зм, Рерихиа́нство, Ре́риховское движе́ние) is a spiritual, cultural and social movement that emerged in the United States in the first half of the twentieth century, though it has been described as a "thoroughly Russian new religious movement", due to its close connection with Russia.

The movement centers on the Neo-Theosophical religious doctrine of Agni Yoga, or the Living Ethics, transmitted by Helena Roerich and Nicholas Roerich. Agni Yoga draws ideas from Theosophy, Eastern and Western religions, Vedic and Buddhist traditions, molding them into Russian culture, too. Agni Yoga is the spiritual foundation of Roerichism.

This movement played a significant role in bringing knowledge of Asian religions to the Western world. Roerichism has an international following and has many thousands of adherents. Some international and regional organizations, whose activity is based on the ideas of Roerichism, arose many years after the death of all the members of the Roerich family.

Roerichism is a spiritual and cultural movement centered on the teachings transmitted by Helena and Nicholas Roerich. It draws ideas from Theosophy, Eastern and Western religions, and Vedic and Buddhist traditions, molding them into Russian culture and Russian cosmism.

Helena Roerich (1879–1955), a Russian theosophist, writer, and public figure, developed in the 20th century, in cooperation with the Teachers of the East (Masters of the Ancient Wisdom), the philosophical teaching of Living Ethics (Agni Yoga).

Helena was born in the family of Ivan Shaposhnikov, a well-known Saint-Petersburg architect. Helena's mother belonged to an ancient Golenischev-Kutuzov family, traceable to Novgorod at the end of the 13th century. Significant members of this family included Prince (Russian: knyaz) Mikhail Kutuzov, field marshal of the Russian Empire; Arseny Golenishchev-Kutuzov, poet of the end of the 19th century; Ilya Golenishchev-Kutuzov, a philologist and poet; and Modest Mussorgsky, a well-known composer. It was a nobiliary family, distinguished not only for its nobility but for its cultural traditions too. Helena was in frequent communication with artists and scientists of the era, such as Vladimir Bekhterev, Alexander Blok, Sergei Diaghilev, Arkhip Kuindzhi, Vladimir Solovyov, Vladimir Stasov, Igor Stravinsky, and Mikhail Vrubel.

In 1901 Helena married Nicholas Roerich. From that time they were inseparable in their life and their spiritual-creative paths. She became his companion-in-arms in all his public and cultural undertakings. The Agni Yoga Society was founded by Nicholas and Helena in 1920 in the United States. Together with her husband she participated in the heroic Transhimalayan expedition in Central Asia (1924–1928). After the Roerich family settled in Kullu Valley, in the Himalayas, they established the Himalayan Institute of the Scientific Studies, and its honorary president was the foundress Helena Roerich.

The years in India were the time of the most intensive work of Helena. Here she completed a major part of the books of the Agni Yoga series. She published fourteen volumes of that series. On the frontispieces of the volumes there is no author's name, since Helena Roerich considered that the sacred wisdom contained therein can not be the author's property. She considered herself an author of three books only, published under different pen-names: "The Foundations of Buddhism" (1927), "The Cryptograms of the East" (1929), "The Banner of the Reverent Sergius" (1934). She maintained very active correspondence with many people from Europe, Asia and America. Two volumes of her letters (Letters of Helena Roerich) were published in Riga in 1940. Helena also did the translations. She translated into Russian extracts from the book The Mahatma Letters to A.P. Sinnett (The Chalice of the East) and also two volumes of The Secret Doctrine by Helena Blavatsky.