The recent wave of randomized trials in development economics has
provoked criticisms regarding external validity and the neglect of
political economy. We investigate these concerns in a randomized trial
designed to assess the prospects for scaling-up a contract teacher
intervention in Kenya, previously shown to raise test scores for
primary students in Western Kenya and various locations in India. The
intervention was implemented in parallel in all eight Kenyan provinces
by a non-governmental organization (NGO) and the Kenyan government.
Institutional differences had large effects on contract teacher
performance. We find a significant, positive effect of 0.18 standard
deviations on math and English scores in schools randomly assigned to
NGO implementation, and zero effect in schools receiving contract
teachers from the Ministry of Education. We discuss political economy
factors underlying this disparity, and suggest the need for future
work on scaling up proven interventions to work within public sector
institutions.