Within a few years of SIOP's founding, other organizations emerged, reflecting an expanding interest in specialized areas of I-O Psychology. The American Society for Training and Development (ASTD), now known as the Association for Talent Development (ATD), was founded in 1944. It focused on the professional development of trainers and facilitators, emphasizing the need for psychological principles in training programs. This organization served as a vital resource for I-O psychologists whose work intersected with training and development. Another critical player in the post-war era was the International Association for Applied Psychology (IAAP), established in 1920 but revitalized after the war. This organization sought to promote the application of psychological principles across different cultural and organizational contexts, thereby positioning I-O Psychology on a global stage. The IAAP facilitated international research collaborations and conferences that allowed practitioners to share insights drawn from various cultural perspectives, thereby enriching the field. The establishment and growth of these professional organizations sparked a proliferation of research and scholarship in I-O Psychology. They provided the infrastructure for professional certifications and guidelines that defined competencies and ethical standards within the discipline. Among the foremost initiatives was the introduction of certification programs that validated the expertise of I-O psychologists, ensuring that practitioners met the discipline’s evolving professional standards.