à Montréal "How many are gifted or talented?" although very important, this question has received little attention from most scholars in gifted education. four major variables are identified that directly impact prevalence estimates: (a) the type of definition endorseddisjunctive or conjunctive, (b) the number of abilities/characteristics included, (c) the minimum selection threshold chosen, and (d) the correlations observed between the abilities included. a range of values was determined for the last three variables. By combining these values, we produced four tables of prevalence estimates, which reveal how these variables interact and how they affect the "how many" question. the results show that both the type of definition endorsed for the giftedness or talent concepts and the selection ratio have a crucial impact on the prevalence estimates. the authors argue that gifted education will never be recognized as a proper scientific field unless its scholars reach a consensus on both the definition and prevalence issues. How many individuals can be labeled gifted or talented? This question, commonly called the prevalence issue, appears quite simple, deceptively so. As we will see below, so many considerations need to be made that no simple answer can be given. The present article aims to explore some of the factors that affect the answer and show how interactions between them modify prevalence estimates. Common sense and simple statistical knowledge do reveal basic rules. For instance, the higher (more selective) the cutoff value chosen (e.g., top 15%, top 5%, or top 1%), the smaller the number of individuals labeled gifted and talented. Similarly, if giftedness and talent can take many forms (e.g., intellectual, social, artistic, athletic), the prevalence will increase as the number of domains or fields increases. Or, if two criteria are highly correlated, those who excel in one of Jean Bélanger is Professor in the Department of Special Education and Training at the University of Quebec in Montreal (UQAM). Professor Françoys Gagné is a French Canadian from Montreal, Quebec. He has been active in gifted education since the early 1980s and has published extensively in that field.