The author proposes four levers to improve teacher quality. Policies should focus on: (a) increase quality applicants, (b) retain high quality teachers, (c) increase turnover of low quality teachers, and (d) improve existing stock of teachers. Existing research provides insight on improving each of these proposed four policy levers in isolation rather than as interconnected parts. Understanding the policy interaction on the resulting teacher supply and different levels of response from current and potential future teachers provides an important channel for further impact. Research suggests that teachers who leave the profession after a few years – (i.e., more experienced teachers) – tend to be higher quality even controlling for average quality of those with similar experience levels. Teachers who leave within the first year; however, are more likely to be low performers. Thus, policies that increase retention of first year teachers could potentially be harmful, depending on the average quality and cost of new hires.