He was born in La Capilla, to parents who were immigrants from Bessarabia. He continued studying Jewish subjects with his father and with a local rabbi. He was a teacher in Buenos Aires in Jewish schools of the Cursos Religiosos network maintained by the Congregación Israelita and ica and in the 1930s was supervisor of the schools of this network in the provinces. Appearing in the local Jewish press, his articles expressed a Jewish national and Zionist position. Yagupsky was director of the Editorial Israel which published many Jewish books in Spanish in the 1940s and in the 1950s. From 1946 to 1948 he directed the Latin American Department of the American Jewish Committee in New York and in 1948 he opened a branch of this institution in Buenos Aires and acted as its director until 1961. From then and until 1968 he was the director of the American Jewish Committee in Israel. In that year he returned to Buenos Aires. Yagupsky translated the siddur and the Torah into Spanish. He published Soliloquios de un judio ("Monologues of a Jew", 1986). In the book Conversaciones con un judio ("Conversations with a Jew", 1977) edited by Mario Diament, Yagupsky shared his thoughts and memories. He edited the journals Comentario ("Commentary") in Buenos Aires and Amot in Tel Aviv. He was also active in Jewish journals in Spanish, Hebrew, Yiddish, and English. In 1988 he received the Prize for Intellectual Merit of the Latin American Jewish Congress.