Citizens of the three East African countries Kenya, Tanzania and Uganda differ much in their expressed support for the political opposition and in their trust in the ruling political institutions of the president, the electoral commission and the ruling party. Citizens in Uganda and Kenya have become more sceptical towards their ruling institutions, while citizens in Tanzania are still very trusting and express much stronger deferential values than is the case in the other two countries, even though Tanzanians have experienced less of democratic changes. How can this difference be explained, and to what extent is democracy being institutionalized in the three countries? Using Afrobarometer data it is shown that democratic constitutional values are an important reason for supporting the opposition in Kenya, but much less so in Uganda and Tanzania. In Kenya, democratic constitutional values are negatively related to support for the ruling institutions, while in Tanzania, the same values strengthen support for the government. A positive evaluation of democratic procedures and government output explains much of the support for the ruling institutions, while a perceived high level of corruption and a low estimation of delivered democratic procedures lend support to the opposition. Kenya appears to have reached a more advanced democratic awareness than the other two countries. While some important democratic institutions have taken root in the three countries, there is still a long way to go before the region has attained stable democracy.