Advocates of the science of reading have argued that (a) teacher preparation programs do not provide adequate preparation to teach code-related reading skills; (b) as a result, teachers lack knowledge of this area of literacy development; and (c) without that knowledge, teachers are unable to effectively teach students to read. In this integrative literature review, we assessed the research evidence for the first claim. We identified 27 studies examining preservice general elementary preparation in code-related instruction, including phonological/phonemic awareness, phonics/decoding, spelling/orthography, and morphology, published between 2001 and 2020. We analyzed the studies to determine (a) how preservice knowledge of code-related instruction has been studied, (b) how preservice teachers' literacy knowledge was defined and assessed in these studies, and (c) primary findings across studies and implications for teacher preparation and future research. We found that the research base largely relied on quantitative multiple-choice assessments that privileged linguistic content knowledge over pedagogical and situated knowledge. The body of research was constrained by narrow definitions of science and knowledge, repetition across studies in methods and data sources, limited samples that overlooked diversity in preservice teachers and elementary contexts, and methodological problems. Thus, we caution against considering the issue of teacher preparation settled, and we offer recommendations for teacher preparation programs and directions for future research.