The Millennium Challenge Corporation (MCC) wanted to evaluate the impact of several large electricity sector investments it was planning in Tanzania, namely, construction of a new subsea high voltage cable connecting Zanzibar Island to the mainland, construction of a new hydroelectric plant and distribution at Malagarasi; and rehabilitation and extension of low voltage and medium voltage networks in four regions. MCC wanted to measure, through a rigorous impact evaluation, whether those activities led to improved health, economic, and educational outcomes at the household level as well as better financial outcomes at the business level.