This paper aims to show how letters, as a genre of literacy, are used in Karagwe in Tanzania, in relation to authority and secrecy. It is shown that literacy, in the form of letters, plays an important role in the negotiation of authority. Authorities as well as ordinary people use letters according to official norms to claim or manifest authority, while grassroots forms of literacy, dominated forms, are used to resist authorities. Through secret messages and letters people find opportunities to resist that are less dangerous than open rebellion, although the effects may be limited because of the secrecy. It is also shown how children are socialized into this pattern of secrecies through literacy as they are used as messengers. When delivering secret letters and messages, they may be said to exercise a passive voice through literacy.