This study investigated the prevalence of transformative experiences, antecedents of transformative experience, and the relation between transformative experience and deep-level learning (conceptual change and transfer) for high school biology students (N = 166). Results suggested that the high school students in our sample typically engaged in low levels of transformative experience with respect to biology, but those students who strongly identified with science and who endorsed a mastery goal orientation were more likely to report engagement in higher levels of transformative experience. Furthermore, a higher level of engagement in transformative experience was positively associated with (a) conceptual change in understanding the concept of natural selection, but not inheritance, at the post- and follow-up assessments and (b) transfer at the follow-up assessment. © 2009 Wiley Periodicals, Inc. Sci Ed94:1–28, 2010