This study examines how intellectual and institutional developments transformed the U.S. Navy from 1873 to 1898. The period was a dynamic quarter-century in which Americans witnessed their Navy evolve. Cultures of progress—clusters of ideas, beliefs, values, and practices pertaining to modern warfare and technology—guided the Navy's transformation. The agents of naval transformation embraced a progressive ideology. They viewed science, technology, and expertise as the best means to effect change in a world contorted by modernizing and globalizing trends. Within the Navy's progressive movement, two new cultures—Strategy and Mechanism—influenced the course of transformation. Although they shared progressive pedigrees, each culture embodied a distinctive vision for the Navy's future.