Implementation represents the stage of the policy cycle that receives less attention in political and public policy practice and theory. Either out of convenience, ignorance, or negligence, politicians and policymakers tend to disregard the crucial importance of the large and complex array of decisions and activities required to implement public policies. Public policy scholarship is not exempt from the relative neglect of implementation. A focus on the study of policy implementation first appeared during the 1970s in the work of scholars like Pressman and Wildavsky (Reference Pressman and Wildavsky1973) and Bardach (Reference Bardach1977), decades later, after the policy studies field had been founded by Laswell, Simon, Lindblom, and other contemporary academics who centred their attention on the decision-making processes of policymakers. Even after its recognition as an autonomous field, reasons, such as the preference of prioritising the study of the politics of agenda-setting and policy formulation processes, a tendency of associating implementation activities with the sub-discipline of public administration and of classifying them as mere administrative issues, or the difficulties of conducting research on implementation at the street-level, which can be more time-consuming, costly, and complex than the analysis of other policy stages, have continued to curb the attention that the analysis of the implementation of public policies should receive to understand the causes and consequences of their success or failure. In the realm of social policy, research on implementation is crucial because the events that unfold during this stage shape a society’s welfare levels.

Social policy implementation researchers face enormous challenges. The provision of welfare benefits and services involves enormously complex sets of activities, performed by large and diverse numbers of civil servants, usually dispersed throughout wide geographical spaces, who inevitably hold substantial discretionary powers in the delivery of public goods and services. Disentangling, analysing, interpreting, and understanding the web of formal and informal rules, as well as the collective and individual decisions and actions of public sector workers and members of target populations involved in the implementation of social programmes, represent some of the most arduous and laborious tasks of social policy scholarship. Researchers who undertake such challenges are the ones willing to travel, both physically and intellectually, to the trenches of policy development, where the hardest battles for policy success are fought.

The articles gathered for this special issue represent outstanding examples of social policy implementation research. The issue was proposed with the objective of convening research on Latin America and Southern Europe, two regions that provide critical empirical settings for advancing policy implementation theories. Notwithstanding salient differences within and between regions, the social policy arrangements of many of the countries that form them share several features, like the familialistic orientations of their welfare regimes, a historical reliance on fragmented social insurance programmes built under corporatist political regimes in the first part of the 20th century with recent significant expansions of non-contributory social assistance programmes, the prevalence of clientelistic networks and practices in the organisation of public bureaucracies and the delivery of social benefits and services, late industrialisation processes, and high rates of informal and self-employment. These and other features make Latin American and Southern European social policies critical case studies for applying, testing, and refining implementation theories that might have emerged from research on Northern Europe or the United States.

The special issue consists of nine articles that address key topics of social policy implementation. The issue begins with a review article prepared by the guest editors, which outlines the main theories, models, and concepts of policy implementation and provides a literature review on the current challenges and opportunities for social implementation in Latin America and Southern Europe. Relevant opportunities identified for both regions include the effective use of discretion by street-level bureaucrats, the participation of civil society actors, and the strengthening of state capacities through vertical and horizontal coordination between government agencies.

Eight articles based on single case studies from Argentina, Brazil, Italy, Peru, and Spain apply various salient theoretical and methodological approaches, across highly diverse policy sectors. The articles analyse the implementation of programmes of central relevance not only for the study of the social policy of each country and region but also, more broadly, for understanding the intricacies of policy development and advancing policy implementation theories and concepts. The articles employ diverse methodological approaches to capture the complexity of implementation processes. Qualitative case studies predominate, utilising interviews with street-level bureaucrats, programme administrators, and beneficiaries (Landini, Reference Landini2025; Mitchell, Reference Mitchell2025; Montesano, Reference Montesano2025). Quantitative analyses draw on administrative data to assess implementation capacity and coordination mechanisms (Busilacchi et al., Reference Busilacchi, De Angelis and Luppi2025). Mixed-method designs combine statistical analysis with qualitative insights from practitioners (Álvarez-Cronin and Noguera, Reference Álvarez-Cronin and Noguera2025; Soler-Buades and Ferraioli, Reference Soler-Buades and Ferraioli2025). This methodological diversity enables triangulation across different empirical strategies while addressing the field’s “dependent variable problem” in operationalising implementation outcomes.

The two articles engaging with street-level bureaucracy theory reveal a common finding that diverges from traditional assumptions about discretion. Montesano (Reference Montesano2025) analyses the implementation of Argentina’s Universal Child Allowance, a pillar of that country’s social policy during the present century. The article shows how front-line officers apply their discretionary power to compensate for institutional weaknesses, adjusting and adapting formal rules to local contexts and needs not considered in the programme’s design, revealing the positive role that the discretion, decisions and informal practices of street-level bureaucrats can play for the improvement of implementation outcomes. Landini (Reference Landini2025) investigated the implementation of an intercultural education strategy in Italy. The strategy aims to respond to increases in cultural and linguistic diversity due to migration and refugee flows. The article analyses the translation of intercultural education policy into school practices at the street level. Research findings also demonstrate a positive effect of the discretion of street-level bureaucrats, in this case, the teachers responsible for policy implementation, who act as policy innovators engaging students and civil society members through participatory practices. This contrasts with deficit-oriented views of discretion common in the hegemonic implementation literature.

Mitchell’s (Reference Mitchell2025) analysis of Argentina’s drug policy also explores the role of civil society in policy implementation. The article extends research on implementation beyond the state apparatus, demonstrating how a severe economic crisis and ineffective government response created opportunities for civil society innovation. Community organisations enabled substance abuse treatment access through local facilities and support networks, illustrating how non-state actors can fill implementation gaps while addressing multidimensional needs overlooked by formal policy design.

Three articles focus on the analysis of state and administrative capacities, multi-level governance and coordination across government levels and agencies in decentralised contexts. These articles show how a national policy can generate divergent outcomes depending on local implementation arrangements. Soler-Buades and Ferraioli (Reference Soler-Buades and Ferraioli2025) and Álvarez-Cronin and Noguera (Reference Álvarez-Cronin and Noguera2025) analyse the implementation of Spain’s Minimum Living Income programme, a national targeted social assistance programme that provides income support to the population in poverty. Soler-Buades and Ferraioli (Reference Soler-Buades and Ferraioli2025) applies administrative burden theory to show how implicit welfare rescaling increased claimants’ learning, compliance, and psychological costs due to coordination failures across government levels – a challenge front-line officers attempted to mitigate. Álvarez-Cronin and Noguera (Reference Álvarez-Cronin and Noguera2025) trace implementation failures to the political conditions during programme’s introduction and the pre-existing complex landscape of 17 regional minimum income schemes, revealing how institutional legacies constrain adaptation. In the third article that addresses administrative and coordination issues, Busilacchi et al. (Reference Busilacchi, De Angelis and Luppi2025) analyse the effects of minimum income programmes on labour market integration in Italy. The research investigates how implementation capacities and institutional cooperation shape policy outcomes across regions. Findings reveal that horizontal institutional networking and coordination between local government employment agencies improve labour market integration outcomes, even controlling for regional capacity differences.

De Sálem Vital and Xerez (Reference De Sálem Vital and Xerez2025) and Maco (Reference Maco2025) contribute to the special issue with articles on social housing programmes in Brazil and the social assistance income transfers programme of Peru. De Sálem Vital and Xerez (Reference De Sálem Vital and Xerez2025) reveal persistent gaps between the design and implementation of the My House, My Life and the Green and Yellow House programmes, alongside financialisation and commodification trends that prioritise real estate interests over vulnerable populations’ needs. In her study of Peru’s conditional cash transfers programme, Maco (Reference Maco2025) suggests that concerns about implementation failures, such as aversion to clientelism, halted expansion from rural to urban areas. Institutional legacies like this one limited the programme’s adaptability to changing poverty dynamics. Together, these studies demonstrate that implementation cannot be understood solely through present-day capacity or coordination; historical patterns of state-society relations fundamentally shape what is politically and administratively feasible.

These eight case studies provide several cross-cutting insights for implementation theory. First, context specificity matters profoundly: the same formal policy design, like Spain’s minimum income programme, or theoretical approach, like street-level bureaucracy and the bottom-up model, can produce divergent outcomes depending on administrative capacity, institutional contexts, structures and legacies, and subnational governance configurations. Secondly, civil society actors may function as both co-implementers and innovators, not merely service recipients – a finding particularly pronounced in Latin American cases where state capacity gaps are larger. Third, implementation failures often stem from design-context mismatches rather than pure capacity deficits: policies designed for stable employment, like Italy’s minimum income scheme, or single-household poverty, like Spain’s minimum income programme, struggle when confronting informal labour markets and complex household structures characteristic of Southern European and Latin American realities.

The case studies covered in this special issue demonstrate that Latin American and Southern European contexts expose theoretical assumptions embedded in implementation frameworks developed primarily from Northern European and North American cases. Familialism, clientelistic legacies, labour informality, and fragmented insurance-based systems create implementation challenges not fully captured by existing models. Yet, these regions also showcase important innovations: civil society’s role in co-production exceeds that typically observed in other Bismarckian or Nordic welfare regimes, and frontline workers’ positive use of discretion contradicts assumptions about street-level obstruction. Research that enables the comparison of causes and features of social policy implementation gaps, outcomes, and successes across these and other regions remains crucial for improving welfare in contemporary societies.