In approximately 1948, The American School of Guadalajara secured a new location by renting a sizable house at Avenida Vallarta #1515. Leadership transitioned to John Sherman during this period. ASFG stood out as the sole bilingual and coeducational institution in the city at that time, attracting families from diverse nationalities and backgrounds. By 1953, the school's enrollment had significantly increased to 450 students. In 1955, Mr. Sherman concluded his directorship, briefly succeeded by Shirley A. de Palos. The school was then owned by Dr. Paul Jensen, who announced his intention to sell it in December 1955.

This led a group of Mexican and American individuals to recognize the importance of an English-speaking school in Guadalajara, prompting discussions on potential ownership. Despite the parents' vote in favor of purchasing the school at a reasonable price, the Board of Directors and Founders decided against the $15,000 USD offer. Subsequently, a constitution was drafted, mirroring the American Schools in Monterrey and Mexico City. On April 27, 1956, the school officially transformed into The American School Foundation of Guadalajara, A.C., solidifying its commitment to education.