APA was founded in July 1892 by a small group of men interested in what they called “the new psychology.” The group elected 31 individuals, including themselves, to membership, with G. Stanley Hall (1844-1924) as its first president.

 

 

APA’s first meeting was held in December 1892 at the University of Pennsylvania. The basic governance of the APA consisted of a council with an executive committee. This structure has continued to the beginning of the twenty-first century: Today, APA has a Council of Representatives with a Board of Directors.

APA’s founding was part of a large number of changes occurring in the United States then, including:

 

 

The emergence of academic disciplines such as psychology, economics, political science, biochemistry and physiology. These new disciplines quickly developed advanced degrees that provided credentials to validate the disciplines’ members as experts.The progressive movement in politics, which called for a more efficient, less corrupt, social order.

 

 

The synergy of these two developments – specialized expertise and rationalized government — helped create the need for trained personnel to fill the new professional niches created by the demands for a more efficient society. Membership growth of the APA was modest over its first 50 years.

 

 

Today, APA is the largest scientific and professional organization of psychologists in the United States, with over 121,000 members, including scientists, educators, clinicians, consultants, and students. It has 54 divisions – interest groups for different subspecialties of psychology or topical areas.

According to en.wikipedia and apa.org