During the last two decades there have been many methodological developments in the design and analysis of phase I, phase II and phase I/II dose-finding studies. Much of these developments originate from the continual reassessment method (CRM), which has gained popularity since its first proposal by O’Quigley et al. (1990). In this paper the author will give a review of the CRM and its related topics. In particular, the author takes a general view of dose-finding and -escalation designs that are extended from or related to the CRM, providing a brief bibliographical introduction of them.