We introduce a synthetic control methodology to study policies with staggered adoption. Many policies, such as the board gender quota, are replicated by other policy setters at different time frames. Our method estimates the dynamic average treatment effects on the treated using variation introduced by the staggered adoption of policies. Our method gives asymptotically unbiased estimators of many interesting quantities and delivers asymptotically valid inference. By using the proposed method and national labor data in Europe, we find evidence that quota regulation on board diversity leads to a decrease in part-time employment, and an increase in full-time employment for female professionals.