This keynote will outline efforts to parse elements of teaching into what have been termed core or high-leverage practices. The effort stems from the persistent critique that teaching lacks a “technical language” for describing teaching (Lortie, 1975) and a desire to better prepare novices for the demands of the classroom. The talk will delve into the socio-cultural theory of practice that undergirds this work and explore how work on core practices has been used in both initial teacher education and ongoing professional development, in both the US and Europe.