Joshua Fishman (Yiddish: שיקל פֿישמאַן — Shikl Fishman; July 18, 1926 – March 1, 2015) was an American linguist who specialized in the sociology of language, language planning, bilingual education, and language and ethnicity.

Joshua A. Fishman (Yiddish name Shikl) was born and raised in Philadelphia. His sister was the poet Rukhl Fishman. He attended public schools while also studying Yiddish at elementary and secondary levels. As he grew up, his father would ask his children at the dinner table, "What did you do for Yiddish today?" He studied Yiddish in Workmen's Circle Schools, which emphasized mastery of the Yiddish language along with a focus on literature, history, and social issues. He graduated from Olney High School. He attended the University of Pennsylvania on a Mayor's Scholarship, 1944-1948, earning a B.S. and an M.S., in history and psychology, respectively. He went on to get a PhD in social psychology from Columbia University in 1953.

He is the father of Monele Fishman, David Fishman and Avi Fishman.

After graduating, he studied Yiddish with Max Weinreich during the summer of 1948. During that time, he received a prize from the YIVO (Institute for Yiddish Research) for a monograph on bilingualism. In 1951-52 he held a position as a research assistant for the Jewish Education Committee of New York. In December 1951, he married Gella Schweid, with whom he shared a lifelong commitment to Yiddish. In 1953, he completed his Ph.D. in social psychology at Columbia University with a dissertation entitled Negative Stereotypes Concerning Americans among American-born Children Receiving Various Types of Minority-group Education.

From 1955 to 1958, he taught the sociology of language at the City College of New York while he was also directing research at the College Entrance Examination Board. In 1958, he was appointed an associate professor of human relations and psychology at Penn. He subsequently accepted a post as professor of psychology and sociology at Yeshiva University in New York, where he would also serve as dean of the Ferkauf Graduate School of Social Sciences and Humanities as well as academic vice president. In 1966, he was made Distinguished University Research Professor of Social Sciences.

In 1988, he became professor emeritus and became affiliated with a number of other institutions: Visiting Professor and Visiting Scholar, School of Education, Applied Linguistics and Department of Linguistics, Stanford University; Adjunct Professor of Multilingual and Multicultural Education, School of Education, New York University; Visiting Professor of Linguistics, City University of New York, Graduate Center. He has held visiting appointments and fellowships at over a dozen institutions around the world, including the Center for Advanced Study in the Behavioral Sciences (Stanford, CA) and the Institute for Advanced Study (Princeton, NJ).

Fishman wrote over 1000 articles and monographs on multilingualism, bilingual education and minority education, the sociology and history of the Yiddish language, language planning, reversing language shift, language revival, 'language and nationalism', 'language and religion', and 'language and ethnicity'. Fishman is the founder and editor of the Contributions to the Sociology of Language book series by Mouton de Gruyter.

Fishman devised the influential Graded Intergenerational Disruption Scale (GIDS), used for determining whether languages are endangered, in his book Reversing Language Shift. The Expanded GIDS was based on this and is used by Ethnologue.