One of 10 children, he was born in 1944 in New York City but raised in Miami Beach, Florida.
In 1972, Kassin returned to the United States at the request of Rabbi Moshe Shamah to establish a high school for the children of the Syrian Jewish community in Brooklyn.
Following his tenure there, he returned to Israel and from 1977 to 1980 directed the one-year program for American youth at Aish Hatorah yeshiva in Jerusalem.
In 1980, Dr. Joe Nissim, president and founder of the Sephardic Educational Center, recruited Kassin to be its first director.
A year later, together with Rabbi Eliyahu Shamoula, Kassin opened the SSC[3] yeshiva in the Old City.