This article describes a project focused on identifying science instructors' conceptions of science literacy and using these conceptions to develop a brief science literacy student self-assessment (SCILIT). We present the rationale and process we used to elicit instructors' conceptions of science literacy, crafted in a meaningful way with input by faculty and graduate student science experts. Next, we explain how we developed a novel student SCILIT self-assessment based on those expert conceptions. We describe our initial efforts using SCILIT in undergraduate general education science courses to explore students' self-perceived science literacy. We discuss the use of SCILIT self-assessment to assess potential progression of students' self-rated science literacy over the course of an academic term, and how this student self-assessment relates to instructor ratings of academic proficiency and science literacy. Finally, we reflect on the use of SCILIT self-assessment to guide instruction and assessment in general education science courses for non-science majors.