In recent years there has been an increased interest in political science in the concept of transparency. The literature has enphisized the effects that government transparency can have, especially on democratic consolidation. Yet there has been very little research focusing on the causes of transparency. This study discusses some of the possible factors affecting government transparency and offers several aggregate tests of their relevance. It enphisizes the mechanisms through which governments adopt institutions supporting transparency in order to signal to their society and to external actors that the information they offer is indeed credible.