This chapter highlights certain trends in Renaissance humanism that serves to illuminate Martin Luther's letters. Time-tested definitions have been emphasized in order to support a study of the humanist tendencies and influences that bore upon Luther's correspondence. Certain questions remain unaddressed. First, to what degree did Luther fit the definition of a humanist? Was he capable of using, even promoting, its various causes and emphases? As his career was a dynamic phenomenon, when and how did he support and employ aspects of humanism and how did this use change as a student, reformer and professor? What was Luther's style in the correspondence and how did he balance form and function? At what points did he employ a polished style and when did he resort to informality? The chapter also discusses the essential aspects from studies of Renaissance humanism, Civic humanism and Christian humanism.