Several major theories — deprivation theory, resource mobilization theory, and the theory of collective action — make different predictions about the effects of repression on political protest. The results of empirical research have been inconclusive as well: some studies have found that repression deters protest, whereas others have found a positive (radicalizing) effect of repression on protest This article proposes a model that explains the different effects of repression, in conjunction with other incentives, on political protest. We first hypothesize that repression has a direct negative (deterring) effect on protest because repression is a cost. This direct effect may be endorsed under some conditions, or it may be neutralized, or even reversed if repression leads to micromobilization processes that raise incentives for protest. These processes are set in motion if persons are exposed to repression, if repression is considered illegitimate by these persons and their social environment (which holds in case of legal protest), and if these persons are members of groups that support protest. Under such conditions repression indirectly increases protest by launching micromobilization processes. These processes and their effects are specified in a model which is tested and confirmed by a panel study of opponents of nuclear power in West Germany.