The changing nature of work is having a profound impact on the human experience, particularly among older workers. Two integrative theoretical and empirical frameworks of adult development over the past 3 decades provide new insights into aging and work in the 21st century. The first framework focuses on adult intellect and the second on work motivation. We provide a brief review of these frameworks, discuss the implications for reconsidering adult work lives in the context of interindividual differences, intraindividual change, and external forces, and argue for greater attention to individual differences in knowledge, skills, and motivation. Six broad themes, arising from the convergence of theory, research findings, and emerging patterns of work, are proposed as guides for forging new directions on the intellectual and motivational aspects of adult development in the world of 21st century work.