The number of individuals entering the workforce with an interest in science, technology, engineering, and mathematics (STEM) careers is low across the United States. Although exposure to STEM careers through the intentional integration of career exploration can positively influence career choice, most student exposure to STEM career exploration occurs in after-school programs and dedicated summer programs but is limited in the general education curricula. The purpose of this study was to understand how and why high school STEM teachers embed career exploration into curricula even though local and national standards do not include these objectives. The conceptual framework for this study is grounded in a combination of constructs from social cognitive career theory and the ideas of situated cognition. This qualitative embedded case study used interview responses and lesson plan artifacts from nine award-winning teachers who embed STEM career exploration activities into curriculum to understand the instructional practices and the perceptions that drive teachers to include these practices. Embedded cases were created from coded interview responses and artifact content. Results confirm the connection between the use of authentic activities and STEM career exploration. Additional findings suggest a continuous connection between authentic activities and teacher-led instructional practices. This study also identified two constructs of social cognitive career theory, self-efficacy, and outcome expectations, as reason for embedding STEM career exploration in curricula. Identifying the reasons for the conscious instructional choices of STEM teachers is instrumental in supporting high school STEM teachers in their work, and ultimately influencing student STEM career choice and career retention in a positive way. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]