In 1876, his ex-employer, Leonard Field, agreed to write Selfridge a letter of introduction to Marshall Field in Chicago, who was a senior partner in Field, Leiter & Company, one of the most successful stores in the city (which soon became Marshall Field and Company). Initially employed as a stock boy in the wholesale department, over the following 25 years, Selfridge worked his way up. He was eventually appointed a junior partner, married Rosalie Buckingham (of the prominent Chicago Buckinghams) and amassed a considerable personal fortune.