The development and evaluation of science students' metacognition, learning processes and self-efficacy are important for improving science education. This paper reports on the development of an empirical self-report instrument for providing a measure of students' metacognition, self-efficacy and constructivist science learning processes. A review of the range of literature related to metacognition, self-regulation and constructivist learning processes resulted in the development of an initial bilingual (English and traditional Chinese) instrument composed of 72 items. This instrument was completed by 465 Hong Kong high school students. The data collected were subjected to exploratory factor analysis and Rasch analysis. The subsequent refinement process resulted in a final version of the Self-Efficacy and Metacognition Learning Inventory—Science (SEMLI-S) consisting of 30 items that can be used for either analysing and focusing on any or all of its dimensions or for assigning scores to individuals that enable comparison between them in relation to their metacognitive science learning orientations. [Copyright of International Journal of Science Education is the property of Routledge. Full article may be available at the publisher's website: http://dx.doi.org/10.1080/09500690701482493]