Gerrer) is a Polish Hasidic dynasty originating from the town of Góra Kalwaria, Poland, where it was founded by Yitzchak Meir Alter (1798–1866), known as the "Chiddushei HaRim".

[7] [8] In his early years, Yitzchak Meir Alter became a close disciple of Simcha Bunim of Peshischa, who preached the ideals of Talmudic rationalism and the pursuit of personal authenticity—later foundational tenets of Ger Hasidism.

The Kotzker Rebbe continued in the ideological tradition of Peshischa, and after he died in 1859, most of his followers accepted Yitzchak Meir Alter as his successor rather than his son, Dovid.

Shortly after accepting the role of Rebbe, Yitzchak Meir was appointed as the Av Beit Din of Góra Kalwaria (Yiddish: גער), where he established his own Hasidic court.

The Gerrer movement flourished under the leadership of Yehudah Aryeh Leib and his eldest son and successor, Avraham Mordechai Alter, known as the "Imrei Emes".

[5] Smaller communities with hundreds of families have also been established in Israel, such as Arad, Beit Shemesh, Kiryat Gat, Hatzor HaGlilit, Haifa, Dimona, Tel Aviv, and Petah Tikva.

[5] Internationally, hundreds of families reside in London, Antwerp, Zürich (where they are the largest Hasidic group), Manchester, Monsey, and Lakewood, with tens more living in Los Angeles, Queens, Montreal, Melbourne, and Chicago.

[12] In 2022, the building was finished when the two wings were joined,[13] making it the largest synagogue in the world, with the main sanctuary seating up to 20,000, and having an area of approximately 35,000 m2 (380,000 sq ft).

[citation needed] Ger has produced some of the most prolific composers of Jewish liturgical music of all time, such as Yankel Talmud (1885–1965), who was known as "the Beethoven of the Gerrer Rebbes".

[15] In October 2019, a group of Gerrer Hasidim under the leadership of Shaul Alter split from the main hassidic court, forming a new kehilla: "Kehilas Pnei Menachem".

[23] In 1948, Rabbi Yisrael Alter established the "Ordinances on Holiness", known as the takanot (called takunes in the vernacular of Yiddish used by Ger Hasidim), which regulate daily living.