Unsatisfied with the weak Orthodox Jewish life and practice in the United States, Kotler returned to Europe to serve as rabbi in the cities of Kurshan and Luknik. Before World War I, Kotler returned to the United States, settling for seven years in Detroit.
Personal life and death
Towards the end of his life, Kotler emigrated to Palestine, where his daughter lived. Following Kotler's death, his son-in-law Yaakov Moshe Charlap renamed his Jerusalem yeshiva in his memory. His great-grandson Zevulun Charlop was the dean of RIETS many decades later.
Works
Kotler authored numerous Torah articles which were published in the various Torah journals of his day, as well as many sefarim (books), including the two-volumed responsaKerem Shlomo (Jerusalem, 1936) and the original work Beis Shlomo (St. Louis, 1927). Many of Kotler's unpublished Torah manuscripts and insights have been lost.