A kollel (also kolel) (Hebrew: כולל \ כּוֹלֵל, kólel, pl. כוללים \ כּוֹלְלִים‎, kolelím, a "gathering" or "collection" [of scholars]) is an institute for full-time, advanced study of the Talmud and rabbinic literature. Like a yeshiva, a kollel features shiurim (lectures) and learning sedarim (sessions); unlike most yeshivot, the student body of a kollel typically consists mostly of married men. A kollel generally pays a regular monthly stipend to its members.

Originally, the word was used in the sense of "community". Each group of European Jews settling in Israel established their own community with their own support system. Each community was referred to as the "kollel of [place-name]" to identify the specific community of the Old Yishuv. The overwhelming majority of these Jews were scholars who left their birth countries to devote themselves to study Torah and serve God for the rest of their lives. The kollel was the umbrella organization for all their needs.

The first examples were Kolel Perushim (students of the Vilna Gaon who established the first Ashkenazi Jewish settlement in Jerusalem) and Colel Chabad for the Russian Hasidim. The Polish Jews were divided into many kollelim: Kolel Polen (Poland), headed by Rabbi Chaim Elozor Wax; Kolel Vilna Zamość was under different leadership; and the Galicians were incorporated under Kolel Chibas Yerushalayim. The last initially included the entire Austro-Hungarian Kingdom, but as each subparty looking for more courteous distribution, the Hungarians separated into Kolel Shomrei HaChomos.

The first kollel – in the modern sense of the term – in the Jewish diaspora was the Kovno Kollel ("Kolel Perushim") founded in Kovno (Kaunas, Lithuania) in 1877. It was founded by Rabbi Yisrael Salanter and directed by Rabbi Isaac Blaser. The ten students enrolled were required to separate from their families, except for the Sabbath, and devote themselves to studying for the Rabbinate. There was a four-year limit on one's membership in the kollel.

Two people can be considered to have spearheaded the kollel philosophy and outgrowth in today's world: Rabbi Aharon Kotler (founder of Beth Medrash Govoha, Lakewood, New Jersey, the largest yeshiva in the US) and Rabbi Elazar Shach, one of the most prominent leaders of the Jewish community in Israel until his death in 2001. The community kollel movement was also fostered by Torah Umesorah, the National Society for Hebrew Day Schools.

Currently, the term is applied in America to any stipend given for yeshiva study and is now a general term for the yeshivah approach to life.

The philosophy of the kollel, in which members are subsisting on support from others, is part of an overall philosophy of some Orthodox Jews, that God desires that the children of Israel primarily occupy themselves in this world with the study of the Torah, and gave certain Jews more of a propensity to work with the intention that they should support the 'learners'. In Orthodox Judaism this has become known as the 'Yissachar-Zebulun' partnership, after the Midrashic legend that the tribe of Zevulun financially supported the tribe of Issachar so that they could occupy themselves with Torah study. The reward of the supporter in the World-to-Come is seen to be equal to that of the scholar's reward.

Most kollels have a scholar serving as a rosh kollel, or head of the kollel. He decides on the subject matter studied by the kollel. In many cases he also has to spend considerable time fund-raising to support the kollel.