field="abstract">The achievement of powerful waste separation management hinges strongly upon the implementation of policies. What is an effective policy to ensure persistent waste separation behavior? To address this question, we examined the effectiveness of regulatory and voluntary policies in a model of the dynamic changes of actual behavior, using a longitudinal field study with four periods (baseline, the first intervention vs. withdrawal vs. the second intervention) from November 2019 to July 2020. Our findings demonstrate that once the regulatory policy was removed or the voluntary policy was adopted (withdrawal period), the weight of unsorted waste increased sharply and individual behaviors returned to that in the baseline period. Even when regulation was enforced again during the second intervention period, more efforts were needed to promote waste separation behaviors for administrators. Thus, we propose that regulation plays a vital role in promoting long-term waste sorting behavior through feedback, observational learning, and habit-forming based on social learning theory. The current study sheds new light on the critical role of long-term regulation for successful waste separation management. Our work opens avenues for policymakers and has broad policy applicability from schools to communities.