Although the Brazilian “Bolsa Família” Program (BFP) was largely discussed due to its economic and social outcomes, little is known about the Information Systems (IS) that support BFP. In the context of BFP, CadÚnico system emerged as the registry for citizens who seek to qualify for BFP income transfers, as well as it is an important source of information for other public policies. This paper presents a case study of BFP’s evolution over decades through the CadÚnico development. We analyze how the CadÚnico system evolved in Brazil from a fragmented, offline databases in the early 2000 to a unified, online registry essential to BFP operation. Based on enrolment operations, the paper explains how CadÚnico first attracted other ministries from the Federal Government and later attracted municipalities to data registering. By analyzing BFP IS, we bring more evidences to the political and incremental nature of IS development in developing countries.