A key question for science educators is how to sustain interest in novel or intriguing scientific phenomena so that interest in science is maintained, with the potential to develop into a more enduring interest as manifested in choice of studies in senior high school and tertiary programs. According to Hidi and Renninger (2006), progress through the phases of interest development depends on the availability of opportunities to engage and re-engage with content of the interest, and on support for taking up those opportunities. In this chapter, The authors investigate the validity of this proposition, examining evidence from early childhood studies, classroom experiences, and large-scale longitudinal studies. Findings from young children's expressions of interest and from research into family factors associated with adolescents' educational development point to the important role of parents and teachers in identifying children's interests and supporting them through provision of opportunities to engage with the interest. When the authors examine the evidence from classroom and curriculum research, they arrive at the same conclusion. For students to have more than a fleeting interest in science, they require classroom experiences that provide opportunities to engage with science activities that connect with their own experiences. Not the least of these is the opportunity to experience science through exposure to scientists and the work of scientists. Findings from a number of studies support the contention that early experiences with learning in general and science in particular underpin later choices - decisions to participate in science activities both in school and in the community as well as choices to study science at higher levels. This wide-ranging evidence points to early childhood experience and to later classroom exposure to science in real-world environments as key to the development of interest in science. When opportunities for triggering interest in science, and ongoing support for maintenance of that interest in science, are features of these environments, students are likely to choose science studies in their last years of high school and to make science a part of their lifelong learning and activities.