Coproduction varies in their formats and is subject to strong heterogeneity with field-specific conditions. Also, the selection bias in coproduction participation concerns the consistency of findings. However, the field is still limited in testing complex relationships between motivators. Therefore, using the Public Opinion Survey on Environmental Health Risk Perceptions and Policy Preferences, this study tests the effect of the salience of environmental and health threats on motivations to active and passive coproduction moderated by internal efficacy and external efficacy through a series of Multiple Moderated Regression (MMR) analyses. This study aims to contribute to the field by capturing more meaningful variations of coproduction motivation and yield practical implications on whether additional government efforts or nonprofits' presence as an alternative problem solver can influence citizens' motivation to coproduce. This study found that the salience of environmental and health threats increases the motivation to participate in both passive and active modes of coproduction negatively moderated by low external efficacy (nonprofit presence as alternative problem solvers) when controlling for the education, race, income, gender, housing status, and political ideology of citizens.