Discrete-trial teaching (DTT) is a widely studied and supported teaching method in applied behavior analysis (ABA). Its use spans decades and has been successfully used to teach skills across various domains and learners. To aid and guide practitioners in using DTT, sets of best practice guidelines have been developed (Ghezzi, Psychol Sch 44(7):667–679, 2007; Green, Focus Autism Other Dev Disabil 16(2):72–85, 2001; Grow and LeBlanc, Behav Anal Pract 6(1):56–75, 2013). However, DTT as a practice and teaching methodology has evolved over the years. Notably, research in which a flexible approach to DTT is implemented has indicated that best practice guidelines, which support the use of a more strict or rigid implementation of DTT, may not be most effective when considering the individual needs of different learners. The purpose of this chapter is to provide a brief history and overview of DTT. Additionally, best practice guidelines will be analyzed and compared to findings of current research in which a progressive approach to DTT is utilized. In closing, recommendations for future research and clinical practice will be provided.