Theo was instrumental in the popularity of Impressionist artists such as Claude Monet and Edgar Degas by persuading his employers, Goupil & Cie, to exhibit and buy their works.
Theo juga mengambil peran dalam kepopuleran seniman-seniman Impresionis seperti Claude Monet dan Edgar Degas dengan membujuk atasannya, Goupil & Cie, untuk memamerkan dan membeli hasil karya mereka.