American Psychological Association membership has declined by over 10% since 2008 despite growing numbers of psychology degrees awarded. Most APA divisions contracted: two by >30%. We examined membership trends in APA and its divisions; changing membership demographics; competition for members among clinical and scientific specialty groups; changing climates in academia, research, and practice; and the impact of technology. Diverse factors contribute to APA's and divisions' challenge to recruit and retain members. Reinvigorating their status as scientific and professional organizations may require realigning mission, priorities, resource allocations, communications, and activities to appeal to and reinforce the trust of psychologists, and demonstrate how they serve the needs of most psychologists. This may require revising APA's governance structure, policies, and operations to meet the profession's challenges and guide its future.