Sara Davila and Mary Scholl share lessons learned in delivering mobile-friendly, online, effective teacher training at scale Developing an action-oriented curriculum was the first step in supporting Panama’s comprehensive English language education reform (Davila, 2025). However, the success of this curriculum depended on a second critical phase: preparing educators to effectively implement it in classrooms nationwide. To bridge this gap, a large-scale professional development initiative was launched, to ensure that teachers were not only familiar with the new methodologies but also equipped to apply them in practice. The training initiative was a collaborative effort between English language specialists, including a