Influenced by Piagetian and Vygotskian research, science educators in the 1970s started to pay attention to students’ ideas in science. They discovered that students had deeply held beliefs that were in conflict with scientific concepts and theories. In addition to misconceptions, other terms such as preconceptions, alternative frameworks, and intuitive beliefs or theories have been used to characterize these ideas. One of the first interpretations of misconceptions is that they are faulty intuitive theories, which must be replaced by the scientifically correct ones. Another dominant interpretation is that they represent category errors—concepts assigned to the wrong ontological category. Both of these views proposed that refutation and cognitive conflict are instructional strategies that can be used to extinguish misconceptions. A different approach to misconceptions is expressed by researchers who argue that misconceptions have their roots in productive knowledge elements. According to this view, misconceptions are productive in some contexts but not appropriate in others and in these latter cases more carefully articulated scientific knowledge is necessary. Yet other researchers argue that misconceptions are often hybrids—constructive attempts on the part of the students to synthesize scientific information with intuitive beliefs and theories. Recent research has shown that misconceptions are not supplanted by scientific theories but coexist with them even in expert scientists. As a result, attention in science instruction has shifted from attempts to extinguish misconceptions to attempts to strengthen students’ epistemic knowledge, and their model building, hypothesis testing, and reasoning skills. Cognitive conflict and refutation continue to be important instructional strategies not for extinguishing misconceptions but for creating awareness in students that their beliefs are not accurate from a scientific point of view. Overall, the discovery of misconceptions has had a tremendous influence in science education research and teaching because it demonstrated that students are active and creative participants in the learning process and that their ideas and understandings need to be taken into account in instruction.