Traditional efforts to increase teacher quality through professional development (PD) have been largely ineffective. A growing body of research on teacher coaching provides strong evidence of its effectiveness as a PD tool, although it also raises difficult questions about whether and how to implement coaching programs at scale. Key considerations for scaling up include: (1) Finding expert coaches able to deliver PD services; (2) Dealing with financial constraints due to the large personnel costs of hiring coaches to meet with teachers on a regular basis; (3) Thinking critically about how to implement organizational structures and systems that provide scaffolded supports to individual coaches without restricting their judgment and flexibility; and (4) Creating a culture of trust andrespect among administrators and staff in order to ease teachers' concerns and increase their willingness to actively engage.