Tomchei Temimim (תומכי תמימים = "supporters of the pure ones") is the central Yeshiva (Talmudical academy) of the Chabad-Lubavitch Hasidic movement. Founded in 1897 in the town of Lubavitch by Rabbi Sholom Dovber Schneersohn, it is now a worldwide network of institutions of advanced Torah study.
Tomechei Temimim was founded by Rabbi Sholom DovBer Schneersohn (the Rebbe Rashab) for the study of Hasidic philosophy (Chassidus) according to the Chabad tradition. He called the students of this yeshiva 'temimim' (sing. "tamim" תמים = pure, perfect)
When Rabbi Yosef Yitzchok Schneersohn (the Rebbe Rayatz) left the Soviet Union in 1927, the yeshiva reestablished itself in Warsaw and later in Otwock, Poland. When in the course of World War II the Rebbe was safely evacuated to New York. The yeshiva first escaped to Shanghai, China, along with some other yeshivot like Mir, and then was reestablished in New York City, where it remains to this day.
The central Yeshiva is housed today in Lubavitch World Headquarters, at 770 Eastern Parkway, with approximately six hundred students. Similarly named yeshivas, many of which are nevertheless formally independent, are to be found in major cities in the United States, Canada, Europe, South America, South Africa, Australia, and the former Soviet Union, and Israel. Many of the branches also perform the functions necessary to grant rabbinical ordination to their students. A significant number of graduates of Tomchei Temimim continue working within Chabad as religious functionaries, whether as shluchim in Chabad Houses or as teachers in schools.