This multiple case study examined high school core content area teachers' expectations and instruction of information literacy. The four cases examined in this study were Kansas high school teachers of English language arts, mathematics, science, and social studies. Vygotsky's theory of learning and development (Vygotsky, 1978; Vygotsky, 1986) served as the theoretical foundation for the study, and the information, technology, and scientific literacy standards (Thompson, Dow, & Lund, 2019), which identify information literacy skills that are common across core content area and library learning standards, provided the nine information literacy standards that were investigated. Data collected through surveys, interviews, and instructional documents indicate information literacy is not consistently integrated into the curriculums of high school core content area teachers. Teachers have different expectations of information literacy and do not teach the same concepts. These inconsistencies reflect that many core content teachers do not use authoritative sources of information literacy, including school librarians, to guide their instruction of information literacy skills. The findings of this research suggest the need for a new lens and model that can be used to explain the collaboration and scaffolding necessary to support teaching of information literacy skills across the curriculum. The zone of instructional partnerships model, which builds on the zone of proximal development (Vygotsky 1978; Vygotsky, 1986) and the intensity of effort (Thompson & Dow, 2017), is a visual image that educators, including school librarians, administrators, parents, and other stakeholders, can use to imagine an education process across the curriculum wherein all educators share common understandings, language, and skills to incorporate information literacy instruction in the context of content area learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]