Lawrence Cremin’s professorial life of scholarship and teaching came to full fruition in the 1960s and 1970s. Through the decades he earned fame as a teacher and mentor. In 1961, he published his most notable book, The Transformation of the School, and engaged in intellectual work that would radically transform the field of the history of education. This chapter explores the development of Cremin’s significant scholarship in this period, its impact on the field, the criticisms of and challenges to his work, and his own concerns about his scholarship. The chapter also examines Cremin’s teaching and his relationships with some of his notable students and advisees. Cremin’s influence as a professional mentor and intellectual inspiration to individual students paralleled his growing international reputation as a leading scholar in the field.