In this dissertation, the researcher describes authentic scientific inquiry (ASI) within three stages of teacher preparation and development: a1) undergraduate STEM courses, b2) preservice secondary science education methods courses, and c3) inservice teacher professional development (PD). Incorporating (ASI)--pedagogy closely modeling the research practices of scientists--is at the forefront of national science, technology, engineering, and mathematics (STEM) initiatives and the Next Generation Science Standards (NGSS). In the first of three research articles, 42 students participated in an introductory astronomy course which employed inquiry-based pedagogy. The researcher administered the Test Of Astronomy STandards (TOAST) pre/post instruction. In the second article, 56 preservice secondary science teachers completed ideal lesson plan scenarios before and after 80 hours of methods instruction. The researcher scored the scenarios using a rubric developed according to the NGSS Science and Engineering Practices, and analyzed the components from the scenarios. The third article surveyed 63 inservice STEM teachers with prior research and industry experience. The researcher highlights teacher ASI perspectives. Overall, teachers incorporated opportunities for K-20 students to use scientific instrumentation and technology to collect and analyze data, work collaboratively, and develop evidence-based conclusions. Few teachers provided opportunities for students to ask scientific questions or disseminate results, suggesting the need that teachers (at all levels) need scaffolded instruction in these areas. The researcher argues that while ASI and STEM PDs are effective for teachers, developing similar interest, on-going communities of practice may provide support for teacher to implement the ASI practices in their classrooms. [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/en-US/products/dissertations/individuals.shtml.]