Medical research works in trajectories. Scientists and researchers must choose to pursue certain scientific pathways and omit others, limited by resources, attention, and time. The trajectory of medical progress is therefore characterized by two crucial characteristics: rate and direction. These two components form the foundation for this book - what are the forces that determine the rate and direction of progress in medicine? This book brings together the worlds of scientific policy, economics, sociology, philosophy, and innovation to describe why the world of medical research looks the way it does. The book also addresses fundamental contemporary issues in medicine, how they influence progress, and how we might improve medical research going forward. The contemporary issues discussed include: flawed incentive structures, a concentration of power and resources among few actors and disease groups, the potential distortionary effects of lobbying by different scientific actors, and missing novelty in drug development.