In December 2015, Australia’s Department of Foreign Affairs and Trade’s (DFAT) Office of Development Effectiveness ODE published the Investing in Teachers evaluation report. Investing in Teachers revealed the absence of evidence of the impact of teacher development investments on teaching practice and student learning. An ongoing multi-year teacher development study series, which is the focus of this symposium, has commenced in response to this finding. The intent of the study is to collect empirical evidence of the impact of teacher development investments in three countries: Timor-Leste, Vanuatu and Lao PDR.