Most future industrial and organizational (I-O) psychology practitioners and researchers initially enroll in an introductory I-O psychology course during their junior or senior year of undergraduate studies, making introductory textbooks their first in-depth exposure to the field and an important knowledge base. We reviewed and analyzed the 6,654 unique items (e.g., journal articles, book chapters) published in 1,682 unique sources (e.g., scholarly journals, edited books, popular press publications) and authored by 8,603 unique individuals cited in six popular I-O psychology textbooks. Results showed that 39% of the top-cited sources are not traditional academic peer-reviewed journals, 77% of the top-cited articles were published in cross-disciplinary journals, and 58% of the top-cited authors are affiliated with business schools and not psychology departments. These results suggest that the science–practice divide in I-O psychology may develop later—perhaps after graduates obtain employment as either practitioners or researchers. Also, results suggest I-O psychology is closer to business and management than social psychology and psychology in general. We discuss additional implications for the science–practice divide, how to define and measure scholarly impact, and the future of I-O psychology as a field, including the movement of I-O psychologists to business schools and the sustainability of I-O psychology programs in psychology departments.