Since the 1990s, thermal remediation contractors have completed more than 600 projects worldwide. What began as an idea to solve the seemingly impossible DNAPL problem has evolved into a commonly applied and trusted solution for source zone remediation; however, it did not happen overnight. This presentation will cover the progress of thermal remediation methods from initial concepts to mainstream applications; we will examine case studies of break-through moments and discoveries; and we will discuss future developments in order to improve method effectiveness, reduce costs, and manage resources.