After directing high school, college and professional chamber ensembles for several years, Belinfante was invited by the management of the Concertgebouw to form "Het Klein Orkest" in 1937, a chamber orchestra for which she was to be artistic director and conductor. Belinfante held this position until 1941, and it made her the first woman in Europe to be artistic director and conductor of an ongoing professional orchestral ensemble. Concurrently, Belinfante made weekly appearances as guest conductor on the Dutch National Radio, and appeared as guest conductor with orchestras in the Netherlands and in Northern Europe. In the summer of 1939, Belinfante attended the master class of Dr. Hermann Scherchen in Neuchâtel Switzerland to perfect her conducting skills. In recognition of her abilities, Scherchen awarded her first prize over 12 professional male conductors also enrolled in that class; the prize also included a debut engagement with the Orchestre de la Suisse Romande in Montreux.,