Samuel Leser “Mommie” Schwarz was born into a Jewish merchant family in the Netherlands. In 1897, he and his brother Julius travelled to New York for the first time, and he remained there until 1902, illustrating magazines and designing book covers and posters. After returning to Europe, he enrolled in the Royal Academy of Fine Arts in Antwerp. But he found the reigning style there not to his liking, and broke off his studies. In the same year, he travelled back to New York. In 1908/09, Schwarz returned to Europe for good, and moved to Berlin where he met the painter Else Berg, a friend from his youth whom he later married.
They stayed in Paris together in ca 1908/09, where they made contact with many other Dutch artists. They settled in the Netherlands in ca 1909/10 and joined the so-called Bergen School. They married in 1920. In the years thereafter, they travelled throughout Europe. Schwarz and his wife were in Amsterdam when the Germans invaded in May 1940, though they remained there. They were arrested in November 1942 and sent to Auschwitz, where they were executed.