The goal of science literacy for all underlies much of today's K-12 science education (National Academies of Sciences [2016]. "Science literacy: Concepts, contexts, and consequences." National Academies Press; Roberts, [2007]. Scientific literacy/science literacy. In S. K. Abell, & N. G. Lederman (Eds.), "Handbook of research on science education" (pp. 729-780). Lawrence Erlbaum). This goal assumes that the citizens of contemporary societies must be able to appreciate the relevance of and draw upon scientific knowledge and practices in a broad range of personal and social issues. Many national science education standards, which aim to promote science literacy for all, focus almost entirely on prescribing the conceptual knowledge and practices that underlie science literacy, with only little, if any, reference to the affective characteristics that need to be fostered in parallel to conceptual knowledge and skills. This position paper highlights why affect is so important for the development of science literacy by critiquing the arguments that underlie many national standards documents and by considering the crucial role affect plays in becoming and remaining a lifelong learner of science. We argue that there is a discrepancy between the science education research literature and many national science education standards in terms of the latter not acknowledging the affective domain as an important education outcome, and that this discrepancy is an obstacle to the attainment of science literacy for all.