Presentation delivered at CIES2017 (Atlanta). Providing teachers guidance, mentorship and encouragement in between formal, face-to-face trainings or coaching sessions is challenging. While school directors and other peers may offer teachers support in some contexts, others may experience difficulties, isolation or discouragement in incorporating new practices into their classroom instruction. This paper presents new research from a controlled study in Malawi that sought to extend in-person professional development trainings with a targeted communication campaign over a familiar, low-cost and ubiquitous medium: SMS text messages.