Despite evidence of quality teaching in Science, Technology, Engineering and Mathematics (STEM) subject domains (ACME 2007, Pollard et al. 2003) and insistence on the part of many national governments on the economic value of STEM, education, recruitment and retention into STEM subject fields and occupations is said to be continually blighted by a ‘leaky pipeline’. In the UK context, schools are seen to benefit from a multitude of external STEM engagement and enrichment providers and STEM engagement initiatives, the contribution of which is to increase pupil interest, enthusiasm and awareness of STEM. However, despite evidence of the positive impacts of STEM engagement on learners, there exists a dearth of understanding related to how principles of STEM engagement can facilitate STEM teachers in becoming more pedagogically innovative and relevant and, therefore, engaging of their learners in the classroom context. Teachers are also at the nexus of tensions between STEM engagement and the pressures of the curriculum, the assessment system and other aspects of formal schooling. In this article, we employ a secondary data analysis of two prominent cases of public engagement in science and technology (PEST) in the UK to elicit combined lessons for STEM engagement and the pedagogical development of teachers. We consider the successes of science dialogue, which as one iteration of PEST, may be a fertile site for learning, in establishing principles of best practice that might be transposed to the development of teachers as more able and effective in the engagement of learners in STEM.