What role does context play in the mind and brain sciences? This introductory article, “Of Means and Ends,” explores that question through its focus on the ways scientists and physicians engaged with and constructed technology in the mind and brain sciences in the twentieth century. This topical issue addresses how scientists, physicians, and psychologists came to see the ends of technology as important in-and-of themselves. In so doing, the authors of these essays offer an interpretation of historian Paul Forman's revisionist and highly contextualist chronology of the twentieth century, which presents the comparatively recent tendency to aggrandize the ends of technology as evidence of a major, epochal transformation in the epistemic culture of twentieth-century American science. This collection of papers suggests that it was in the vanguard of such fields as psychology, psychiatry, and neurophysiology in North America and Europe that the ends and applications of technology became important in-and-of themselves.