On July 8, 1947, an American library with 3,000 volumes was opened at Wilhelmstraße 15, which was primarily intended to be available to German readers free of charge and to serve "re-education". Here, readers could find "... beautifully printed and bound American literature of a fine intellectual, scientific, political, medical and technical nature", as one journalist noted. This first open access library in Wiesbaden also offered German-language titles. Attached was a magazine room with scientific and entertaining magazines and periodicals.

Colonel MacMahon formulated the guiding principle of the facility at the opening: it was about "establishing a solid road for the exchange of truth and knowledge". The library, which included rooms for film screenings, lectures and exhibitions, had been known as the Amerikahaus since 1948 and was the sixth of its kind in Hesse. In March 1948, the number of books had already tripled and the total number of permanent readers amounted to 3,500. There was a separate children's library for children aged eight and over. "Our institution is a free, cultural enterprise, supported by a free people in the interests of the German public. We don't ask anyone to come here. But everyone who has been here once will come again. The salaries of the employees are paid from a special fund and are not at the expense of the German public ...", explained the director of the Amerikahaus, Emil P. Jallouk, who was assisted by 25 German employees.

On March 1, 1950, the Amerikahaus moved into the spacious rooms of the Villa Humboldt on the corner of Blumenstraße, which had previously been used as an American officers' mess. A German-American community kindergarten was set up on the top floor, with tables, a checkroom, a washroom and miniature toilets. There was a magnificent children's playground in front of the building. The grand opening ceremony with Prime Minister Christian Stock and Colonel James R. Newman took place on May 17, 1950. The library now contained 20,000 volumes, a lecture room with 120 seats as well as discussion, music and reading rooms and a movie theater. The new Amerikahaus represented a "significant enrichment for the spa town", said Lord Mayor Hans Heinrich Redlhammer in his speech.

In addition to musical performances, the varied program of events included illustrated lectures on contemporary American painting, the history and culture of Old Mexico and Swedish opera. Lectures on topics such as church music and religious life in Sweden and on the plans for the new spa district, an exhibition on "non-objective painting" with 400 American and European works, free English courses and film screenings rounded off the program. In the fall of 1953, the Wiesbaden Amerikahaus had to be closed due to excessive costs. The books were initially transferred to the Wiesbaden Museum, where they remained available, but were later transferred to the Amerikahaus in Frankfurt am Main.