Strategising quality teaching in science, technology, engineering, or mathematics (STEM) domains turns focus to teachers' capacity to teach these subjects (UWIRE Text 2017) when they are not suitably qualified in them. Against the backdrop of research that claims that 75% of the fastest growing occupations will require STEM skills, this investigation provides new information about lived experiences of, and those surrounding, out-of-field teaching practices in STEM subject areas, and the implications these experiences have for teaching and learning environments (Office of the Chief Scientist 2014). The out-of-field teaching phenomenon is defined in this paper as occurring when teachers teach subjects or year levels outside their fields of qualification or expertise. The qualitative investigation applies a Gadamerian theoretical philosophy to develop in-depth understanding through the shared perceptions of educational directors, principals, and the lived experiences of teachers and parents from two countries. Leadership perceptions and the complexities involved in out-of-field teaching practices in science and related subject areas are investigated through the lens of multiple interviews, observations, and document analyses. Concluding remarks offer recommendations for educational leaders, reflections on improvement strategies and educational policies. Proposals for further research of the out-of-field teaching phenomenon's impact on STEM subject areas are offered.