Teachers' values, beliefs, and self-confidence are critical components of decisions educators make every day. The purpose of the study was to examine the relationship between secondary science teachers' epistemology and self-efficacy on science instructional practices and conceptualization of student research experiences rooted in the Next Generation Science Standards. A mixed methods explanatory sequential design was utilized by administering the Science Teachers' Beliefs About Science (STBAS), Self-Efficacy to Teach Science in an Integrated STEM Framework (SETIS), and the Science Instructional Practice Survey (SIPS) to secondary science teachers. A follow up semi-structured interview was administered to gather an understanding of the conceptualization of science instructional practices related to student research experiences. Quantitative findings that emerged were that the SETIS total significantly predicts SIPS critique. The combination of predictor variables did not contribute significantly to SIPS instigating, SIPS data, SIPS modeling, SIPS traditional, and SIPS prior. Qualitative findings that emerged were that teachers conceptualized science instruction as a learner centric classroom environment that engages students, while recognizing student apprehension in exploring the nature of science. Teachers' prior educational and professional experiences expand their skill set and influence beliefs despite the challenges of limited funding, time, and mandated curriculum. Additional findings that emerged were a description of how teachers' conceptualization of scientific knowledge represents a paradigm shift occurring in science education as teachers use creative, inclusive instructional strategies to ensure that all students achieve higher order thinking skills at a high level of rigor. Teachers promote student engagement in authentic science practices that resemble the practices of professional scientists and act as guides to knowledge acquisition, whereas a subset of teachers may lack full understanding of the difference between authentic student research and library-based research. Qualitative findings informed how secondary science teachers conceptualized student research experiences in the classroom. The study expanded upon the understanding of the interactions between secondary science teachers' epistemology, self-efficacy on science instructional practices, and conceptualization of student research experiences rooted in the Next Generation Science Standards. [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.]