This article considers the role of social movement allies in Congress in advancing pro-environmental legislation. We argue that compared to sponsors of legislation who hold moderate views, sponsors with extreme ideological positions will be less likely to produce legislation desired by the environmental movement. We also argue that protest and organizational advocacy by constituents will increase the rate at which sponsors enact environmental legislation. Using event history techniques that follow over 12,000 environmental bills from 1973-1996, we find support for the argument that environmental bills are more successful when sponsored by legislators who have environmental voting records closer to the median voter in Congress, compared to bills sponsored by representatives holding more extreme positions. We also find that the number of environmental lobbyist organizations has a positive effect on the speed of enactment of environmental legislation, but that protest by constituents does not affect the speed of the bill’s passage.