Gastrointestinal endoscopy has grown increasingly more complex as the field has evolved over the past several decades, now requiring the practitioner to become proficient at many techniques. This chapter traces the evolution in training from the self-taught pioneers of the early days to the advent of formal proctored tutelage that remains the mainstay of training in this field. It also relates the emergence of numerous innovative learning tools that have already served to further transform training in gastrointestinal endoscopy. In the 1970s, as upper endoscopy and colonoscopy were becoming established as important modalities, other models were developed. The chapter describes the development of simulator-based instruction from the creation of realistic models to their validation and growing importance in endoscopic training. Lastly, it addresses a number of novel principles of education in endoscopy that have paralleled the growing availability of these new teaching tools.