Democracy requires citizens’ opinions in the political process and comprises mechanisms through which these can be realized, including participation. Citizens’ concerns about environmental issues, conditions, and topics are wide-ranging and varied, according to public opinion research, and intersect in important ways with political structures. Although recent public opinion polls reveal these environmental concerns are extensive, questions remain about their distribution globally, and how they relate to environmental attitudes and behaviors. In this chapter, I review the cross-national literature on public opinion on environmental issues and concerns over the past few decades and emphasize recent work. I then provide a synthesis of research on participation with application to the environment, broadly construed, cross-nationally. Throughout the chapter, the goal is to characterize the multifaceted relations among pluralism, participation, and public opinion and how they intersect with environmental issues.