What cultural and structural factors allow conflict in a social movement organization to persist over long periods of time? Using data gleaned from interviews, archival materials, newspaper articles and online sources, I examine the Sierra Club's conflict over immigration policy, an issue which has persisted for decades without clear resolution. I argue that ideology accounts for some activists' position on club policy, while others based their stance on strategic concerns, which were linked in part to forces external to the club. At the same time, the democratic structure of the Sierra Club has allowed factions to continue working towards their own agendas. This case reveals a more complicated connection between ideology and strategy than previous studies have indicated and illuminates how intense conflict may not necessarily be associated with dramatic outcomes.