Though Montessorians have existed in the United States for nearly a century, a distinctly American version of the system did not begin to take hold until the late 1950s. What was referred to at the time as the "second spring" was actually a remarkable moment not just for Montessori education, but also for American culture at large. For the Montessori movement, the years 1959 to 1963 witnessed rapid growth, turmoil, and the establishment of educational, political, and ideological patterns that still influence the movement today. In this article, the authors trace what happened in those years, why it happened, and the impact those events had on the subsequent development of Montessori education in the United States as they look at the historical context surrounding those events in order to provide a richer understanding of the origins of the American Montessori identity. A closer look at the early years of the movement reveals a complex story of two strong personalities, Mario Montessori and Nancy McCormick Rambusch, who shared a deep commitment to the Montessori ideal, and who squabbled endlessly over how to realize that ideal.