Individual decisions have to be aggregated to make group decisions. Markets aggregate decisions by consumers and producers into prices that might reflect social values. But markets allow and generate inequalities, and many aspects of human well-being and the environment do not have market prices. In large societies, direct voting on some policies is possible but most voting is for representatives who become part of a larger policy system. Deliberation is an ideal that underpins most justifications for democracy. It can be linked effectively to scientific assessments at the local to regional level. Ways to use deliberation at the national or global scales require further experimentation. In the United States, high levels of polarization challenge the idea of public deliberation. New technologies will create further challenges for sustainability decisions. Identifying strategies to move forward requires understanding variation in the public and drawing on strategies for nonviolent social change and conflict resolution.