Despite efforts to provide basic improved sanitation to the world's poor, 2.6 billion people still lack improved access. The barriers to providing sanitation are both technological and non-technological. To explore aspects of appropriateness, six communities in rural Bolivia were studied, with a range of wastewater treatment, from flush latrines to centralized sewers. We demonstrate that appropriate sanitation systems in these communities are defined by modular technology and infrastructure, accessibility, minimal use of resources, a representative and accountable water committee, and community training. In the Bolivian communities studied here, condominial sewer systems most closely approached the appropriate technology characteristics we measured.