The UN's 2030 Agenda for Sustainable Development and its 17 SDGs present a global plan addressing critical issues. While primarily focused on national governments, the increasing consensus is that local implementation is crucial due to the significant role of local governments in delivering SDG targets. However, SDG localization presents challenges, including translating the SDGs into local contexts, integrating them into decision-making processes, financing implementation, and developing locally adapted monitoring frameworks. Successful SDG implementation hinges on effective policy integration, fostering cooperation across policy sectors to maximize synergies and minimize trade-offs between SDGs. Policy integration, however, is complex. Challenges stem from the ill-defined nature of the concept, often conflated with policy coherence or the nexus approach; the traditionally siloed nature of local governance; and the need for coordination across departments, joint prioritization of objectives, and evidence-based mechanisms to identify goal and target interactions. Voluntary Local Reviews (VLRs), mirroring the national Voluntary National Reviews (VNRs), are increasingly used by local and regional governments (LRGs) to address these challenges. While initially lacking a formal definition, recent guidelines from various UN bodies have established principles and components for VLRs. These guidelines emphasize policy integration, particularly concerning synergies and trade-offs and vertical integration between VNRs and VLRs. However, they often lack clarity on operationalizing integration. Existing research highlights several VLR benefits, including setting local priorities, facilitating policy integration, feeding into VNRs, and providing evidence-based monitoring tools. Nevertheless, empirical evidence corroborating these claims is limited. This paper addresses this gap by exploring VLRs as instruments for policy integration, examining how the VLR process contributes to it across three dimensions: motivations, design, and outcomes/impact on policymaking.

The literature on SDG implementation highlights the critical need for effective policy integration at the local level. However, existing research often struggles to define and operationalize policy integration, sometimes conflating it with related concepts like policy coherence and the nexus approach. Studies emphasize the challenges posed by siloed governance structures and the need for cross-departmental coordination, joint prioritization of objectives, and evidence-based mechanisms to manage synergies and trade-offs between SDGs. The role of VLRs in facilitating SDG localization is gaining attention, with some research suggesting their potential to improve policy integration, but empirical evidence remains scarce. This study builds upon this existing literature by providing a detailed empirical analysis of the VLR process in a diverse set of frontrunner cities, offering insights into the actual mechanisms through which VLRs contribute to policy integration.

This study employs a qualitative research design using thematic analysis of semi-structured interviews and an open-ended questionnaire. Data were collected from 14 participants (11 interviews, 1 questionnaire) representing 12 frontrunner cities that conducted VLRs between 2019 and 2020. The cities selected represent diverse geographic regions and levels of SDG implementation. Participants were city officials directly involved in the VLR process, ensuring a rich understanding of the internal workings and decision-making involved. The interview protocol guided discussions about motivations for conducting VLRs, the design and implementation of the process (including interdepartmental work and stakeholder engagement), and the outcomes and impact on policymaking. Data analysis involved a combination of deductive and inductive coding approaches, employing a codebook initially structured around three main themes (motivation, design, outcomes) informed by existing literature on policy integration. Multiple rounds of coding and refinement were undertaken to ensure reliability and validity. Thematic analysis identified recurring patterns and themes across the data, offering insights into the contribution of VLRs to policy integration.

The analysis revealed three primary motivations for conducting VLRs: external demands (international organizations and city networks), an organizational drive to localize the SDGs, and a desire to foster policy integration. External demands often provided incentives, legitimacy, and resources. Local stakeholders also played a significant role, providing additional support and diverse perspectives. The organizational drive involved operationalizing the 2030 Agenda and establishing monitoring frameworks. The VLR process itself involved significant interdepartmental work and stakeholder engagement. Cities employed various strategies for interdepartmental collaboration, including mapping exercises, facilitated conversations, and ad-hoc working groups. Stakeholder engagement encompassed a range of methods, such as surveys, workshops, and public forums. Three key ways VLRs contributed to policy integration emerged: 1. **Facilitating Cooperation:** VLRs fostered cooperation and identified interdependencies between different policy sectors within local governments. This led to reformulating existing policies or creating new instruments, particularly in areas like procurement, mobility, education, gender equity, climate action, and disaster mitigation. 2. **Creating New Instruments:** The VLR process facilitated the creation or improvement of policy instruments for measuring SDG progress and establishing baselines for action. Examples included standardized evaluation tools, reporting frameworks, and online platforms for tracking local sustainability indicators. 3. **Enhancing Sustainability Competencies (SCs):** VLRs enhanced the SCs of involved staff. Participants reported gaining systems thinking, futures thinking, and interpersonal skills. This capacity-building proved beneficial for addressing complex challenges and promoting policy integration. While VLRs primarily impacted procedural and organizational aspects, their impact on substantial restructuring of governance paradigms was limited. This might be due to the lack of an explicit mandate for transforming governance structures, the bottom-up nature of many VLRs, and the focus on reporting progress rather than systemic change in early adoption phases.

This study's findings highlight the significant, albeit nuanced, contribution of VLRs to policy integration. Although explicitly fostering policy integration was not a primary motivation in most cases, the design and implementation of the VLR process resulted in improved inter-departmental cooperation and the creation of new policy tools. This suggests that the VLR process itself acts as a catalyst, encouraging reflection on the interconnectedness of SDGs and the benefits of integrated policymaking. The limited impact on deep governance restructuring is consistent with other studies emphasizing the difficulty of transforming entrenched policymaking paradigms. The fact that the cities in this study were early adopters of VLRs may also have played a role, with their primary focus being on initial progress reporting. The findings emphasize the role of VLRs as procedural policy instruments, facilitating coordinated thinking and structured policy appraisal. This contributes to eliminating redundancies and inconsistencies, leading to more holistic solutions to advance multiple SDGs simultaneously. The creation of monitoring and evaluation tools, such as open-source platforms, enhances accountability and facilitates comparative analysis. The unintended consequence of enhancing staff sustainability competencies is particularly notable, given the established link between capacity and effective policy integration. Future research should explore institutional and political aspects of VLR implementation and measure outcomes across different policy domains.

This study demonstrates that while the primary motivation behind VLRs might not always be policy integration, the process itself significantly contributes to it by fostering cooperation, generating new policy instruments, and building sustainability competencies. The limited impact on deep governance restructuring suggests a need for clearer mandates and greater resources for integrating the VLR process into broader governance reforms. Future research should investigate the long-term effects of VLRs on policy integration, especially in cities that may not be early adopters, and explore how to best leverage VLRs for more systemic changes in governance structures to maximize their impact on achieving the SDGs.

This study's qualitative approach, focusing on a limited sample of early-adopter cities, limits the generalizability of findings. The cross-sectional nature of the data prevents establishing causal relationships between VLRs and long-term policy integration outcomes. The absence of cases from the African continent represents a geographic limitation. Further research incorporating quantitative data and a broader geographical representation is needed to strengthen the generalizability of findings.