[6] Following his father's request for assistance, Yisrael began leading a group of young scholars within the Gerrer community, guiding them with spiritual teachings and personal instructions.

As the new Gerrer Rebbe, Yisrael worked to rebuild the Hasidic movement, increasing its influence and shaping its future direction.

He gathered the remaining Gerrer Hasidim who had settled in Israel before the war, along with Holocaust survivors, and sought to bring back those who, or whose families, had distanced themselves from the Hasidic movement.

He is considered one of the major figures in the rebuilding of the Haredi community after the Holocaust, particularly in establishing public norms regarding modesty, gender segregation, and separation from secular culture.

In addition to his role as Rebbe and leader of Gerrer Hasidim, Yisrael also served as the chairman of the Council of Torah Sages.

Through this position, he exerted significant influence over the policies and direction of Agudat Yisrael, a movement co-founded by his father, Rabbi Avraham Mordechai Alter, known as the "Imrei Emes".

Yisrael placed a strong emphasis on Jewish values, particularly modesty, education on safeguarding the covenant, and separating from permissive, secular society.

He viewed these values as foundational to the survival of the Jewish people and believed that strict observance could avert severe decrees upon Israel.