The STEM acronym permeates educational research and practice. While the potential pedagogical merits of STEM as an opportunity to integrate knowledge from the contributing disciplines and achieve a holistic understanding are well-documented, little is known about how out-of-field teachers contend with contributing to such a vision in practice. With an intended audience of STEM teacher practitioners in mind, this chapter focuses on international expert views of technology (T) and engineering (E) in out-of-field teaching of integrated STEM. The presented views were solicited from experienced international researchers, education practitioners, and professionals in science, technology, engineering, and mathematics. Experts’ views emerged as five overarching themes that primarily identified: the importance of maintaining subject integrity, the implicit nature of technology and engineering in teaching activities, the centrality of engineering design processes, the necessity of collaboration and cooperation, and the need for specialised teacher competence. The emergent views have practical implications regarding engineering design and design-based teaching for informing curriculum design, teacher education programmes, as well as STEM textbooks and resource composition. The chapter closes by illuminating the question as to whether integrated STEM remains a sought epistemological position or only a method to teach STEM subjects, a dilemma whereupon our future work with STEM experts shall continue to explore.