With rapid urbanization, environmental problems like green space shortage and urban flooding become prevalent. Identifying effective policymaking and implementation is critical in order to solve these problems. This dissertation addresses four theoretical topics in the context of urban green infrastructure: policy entrepreneur, institutional response to club goods, quasi-public-private partnership, and policy goal ambiguity. Each is exemplified by a causal case study. Data were collected through participant observation, field trips, semi-structured interviews, and crowdsourcing. Chapter 1 takes a longitudinal perspective and examines the dual role of policy entrepreneur and policy implementer in reaching the final policy goal of mandating vertical greening in the law in Shanghai (1992-2016). Usually, policy implementer and policy entrepreneur are two distinct identities and studied separately. This paper provides an unusual counterexample, exploring how the two intertwined identities may influence the entrepreneurial strategies and further influence the incremental policymaking process. Chapter 2 illustrates how government involvement may facilitate club-good development by investigating the nascent for-profit shopping mall roof garden (SMRG) development. SMRGs, established by developers to provide an amenity to mall customers, are in nature club goods. Although the government appreciates SMRGs given their positive externalities (e.g., recreation, stormwater mitigation), existing public policies fail to respond to SMRGs’ cross-sector nature, leaving significant financial, legitimacy, and oversight gaps unattended. The research suggests that government involvement can better facilitate club-goods’ sustainable development by creating an enabling institutional environment, which includes optimized policy design and coordinated cross-department collaboration. Chapter 3 focuses on the rarely studied phenomenon of the Quasi-Public Private Partnership (QPPP) in non-liberal societies. This work offers a general definition of Quasi-PPPs and identifies factors that influence the PPP to QPPP transition. In the case of eco-environmental service provision, the PPP-QPPP transition occurred in two stages. First, the eco-environmental service partnerships, initially established as PPPs, became inoperable with inexperienced partners and unsupportive markets. Second, with financial bailouts from the government, the private partner became a subordinated partner in a consortium between private partners and State-Owned Enterprises, and PPPs transitioned to QPPPs. In a non-liberal society, when the three critical PPP assumptions are violated (competent partners, supportive market, and horizontal partner structure), PPPs are more likely to transition to QPPPs. Chapter 4 examines how policy goal ambiguity influences policy implementation outcomes, exemplified by the Sponge City Program (SCP) implementation. SCP is a centrally-initiated program, requiring mainly the use of green instead of gray infrastructure to manage urban stormwater. When implemented top-down, three cross-level, layered goals of sustainability, stormwater management, and resident satisfaction became incoherent and vague in terms of priority and measurement. The research demonstrates that in a program with multiple policy goals, the goal priority ambiguity allows implementers the discretion to decide the order of goals to manage interest conflicts. Moreover, the goal measurement ambiguity allows implementers to decide the degree of their commitment to each goal, and to interpret the desired performance of a goal. Such ambiguity-caused discretions drastically inhibit the achievement of the sustainability policy goal.