Over the last decade, research from manydifferent countries has demonstrated the important roleplayed by teachers in increasing students’ learning andimproving their academic performance. Studies from countriesas different as the US and Indonesia have shown the enormousbenefits that follow from having adequate and effectiveteachers working in a country’s schools. In Indonesia, avalue-added analysis of student learning outcomes found thatthe more teachers know, the greater the improvements in thelearning competencies of primary and junior secondarystudents. In the US, better teaching in elementary andsecondary schools has been shown to increase students’college participation rates, raise their subsequentearnings, and improve other long-term outcomes. Providingteachers with good quality professional developmentopportunities has been shown to be an effective way ofincreasing their competencies and improving student learningoutcomes in many different settings. A series of systematicreviews have been undertaken recently to assess the impactof different interventions on student learning outcomes indeveloping countries. One of the most consistent findingsfrom these reviews has been the positive and significantimpact that interventions to strengthen teaching practice,introduce innovative instructional methods, and strengthenteachers’ subject knowledge can have on student learning.However, in many countries, such professional developmentopportunities frequently fail to meet even minimum levels ofquality and fall short of what teachers want and need.