The notion of SI is not new. Schumpeter [14], Ogburn [15] or Polanyi [16], among others, have already referred to this concept more or less explicitly during the 20th century. However, the meaning of the notion has changed throughout history, according to the institutional context of each era and place [17]. In the 21st century, SI has been used interchangeably to refer, for instance, to new entrepreneurial solutions (models, processes, products, etc.) to social challenges and needs [18]; to new practices that affect social structures and the general well-being of the population [1]; or to the satisfaction of human needs through new social relations and empowerment processes [19].

Although it is accepted that SI is a phenomenon dependent on the territorial context [20], much of the literature neglects the particularities of rural areas. This gap has started to be bridged in recent years through the work of authors of rural tradition [5,9,21], where the understanding of the SI phenomenon finds several points of convergence. In general, it is conceived as a process (i) based on collective actions and transformations within social relations [9,22], (ii) where the main changes and outcomes occur on intangible elements [5,9,23], (iii) whose originality or novelty is relative to the context in which it is developed [23], and (iv) in which civil society is involved to different degrees [24,25]. In the present research, we gather these common points, and define SI as a process of reconfiguration of social relations between actors that leads to new forms of action in pursuit of collective goals, whose main result is the creation of social value [26].

We understand SI processes as those reconfigurations in social relations that occur in three dimensions: actor networks, attitudes, and governance arrangements [22]. SI initiatives can include new actors, new roles within existing networks, new values and motivations, and new coordination structures and mechanisms. SI transforms the way local actors interact in addition to how local communities connect and coordinate with external actors [27]. SI initiatives are identified as original and more efficient ways of social organization to achieve collective goals. They are processes recognized as innovative in their context and do not need to be replicable or scalable.

Some authors argue that rural societies are an appropriate context for SI, insofar as they represent small communities where more sociable and cohesive forms of life persist [23,28]. Simultaneously, there is some debate as to whether this is a process driven primarily by demands from the population to satisfy unmet social needs (demand-led), or by opportunities to generate new activities and improve the governance of rural territories (opportunity-driven) [28,29]. The different impulses and the actors’ perception of the community’s needs and opportunities determine, to a large extent, the intensity of SI and its transformative capacity [27].

Therefore, SI’s contribution to rural development has multiple dimensions. On one hand, it is a means to find new and more effective solutions to traditional rural challenges, such as the lack of facilities and services [22,24,30]. On the other hand, SI is an end in itself that allows the reconnection of rural societies internally and externally. The first process refers to the incorporation of new groups of actors, mainly social and/or economic, in local development dynamics and the generation of social assets that improve the future performance of communities. Examples include greater social cohesion, sense of place or capacity-building [24,31].

Regarding the second process, rural territories benefit from the interactive nature of SI, associated with new social interactions that are not limited to the geographic area of the local community. During SI processes, actors from other territories are involved and different forms of coordination with organizations at different territorial scales are established [7,32]. This contributes to the articulation of rural communities with their socio-institutional environment (regional governments, firms, or third sector networks, etc.) and impacts their ability to access resources and their participation in decision-making processes [24]. Therefore, improved governance mechanisms adapted to the reality of these areas can be generated. The internal and external reconnection of rural actors are not only compatible, but complementary and necessary phenomena for the socioeconomic development of rural communities [33].

In essence, SI is a process of innovation in social relations. It contributes to rural development by configuring new patterns of interaction between actors, whether these be individuals or organizations. Actors are the protagonists of reflexivity processes, through which they monitor the territorial context and deliberate about the activities and events that occur within it, with the aim of developing, implementing, and modifying ideas [34]. Actors also undertake preparatory actions, such as the construction and dissemination of narratives [35], in order to encourage a critical mass of individuals to participate and make the idea of innovation a reality [22]. Two aspects are relevant regarding the effective action of actors. Firstly, it depends on the agency or personal capacity to take action and transform the existing institutions and social system [36]. Secondly, agency is embedded in social structures and power relations that limit or encourage, to a greater or lesser extent, the possibilities to act and the scope of actions [34].

The role of actors is inherently linked to leadership. The leadership approach is interesting to address the missing link between the agential dimension of SI and how agents of change confront structural–contextual forces. Leadership is increasingly recognized in SI literature as a quality of groups, a view that challenges the conventional concept of leadership as individual leaders influencing followers [37,38,39]. Instead, leadership is a relational process in which actors are socially embedded [37]. While certain key individuals are often important, it is the production of collective capacities that contributes to democratizing SI initiatives and multiplying their effects [38]. Relational leadership in SI should be seen as a distributed practice of actors across sectors and scales that transform individual efforts into collective achievements [37,38]. However, there is not a set of practices or premises for effective leadership in SI. The specific conditions affecting a community or region determine the capacity for leadership to emerge and develop [40]. Leadership is composed of elements of physical, relational and emotional proximity, which provide shared vision and social legitimation in SI initiatives [41,42].

In rural areas, community leadership tends to be understood as inclusive, goal-driven and undertaken by a group of people that are willing to share power with others [43]. These groups of people can be configured by hybrid combinations of public and private actors. However, civil society usually plays a leading role in rural SI. In rural territories, this fact is of particular interest, to the extent that they are recognized as places where the presence of conventional innovation actors (universities, technological institutes, and companies) is lower, and where the agglomeration factor (a determining factor for creative processes and spill-overs) is replaced by low population densities [44]. Thus, civil society self-organization and networks with actors outside the territory are recognized as defining elements of SI in rural areas [24,25,32,45]. These features can be clearly linked to the quadruple helix model [46].

Almost by definition, the leading role of civil society is also attributed to the leadership of social economy (SE) entities. Anglo-Saxon studies describe social enterprises as promoters of SI initiatives, mainly because they are enterprises whose social and collective objectives are more important than economic ones and, therefore, they continuously pursue new solutions to meet social needs [28,47]. From the European SE tradition, these entities are also significant for SI because they incorporate participatory and inclusive processes in their performance and can, therefore, promote new social relations and the empowerment of new social groups linked to their activities [48,49]. For example, the SI-DRIVE project shows that NGOs or non-profit organizations are the leading actor in almost 50% of the over 1000 SI initiatives examined [50].

In the rural literature, the connection between SE and SI is still underexplored. In the Anglo-Saxon context, recent studies highlight that the importance of social enterprises in SI processes is due to their capacity to integrate material and immaterial aspects of their rural environment, to combine economic and social relations, and to act as intermediaries between the rural community and key actors outside the territory [51,52]. In Spain, these relationships have been especially explored in southern regions, where the role of agricultural cooperatives in activating SI processes and combating depopulation has been demonstrated [53,54].

SI goes beyond the leadership of civil society. The nature of this phenomenon requires cross-sectoral interactions at different scales [9,50]. The public sector is one of the actors that explain this hybrid character of SI. Its role is usually described as complementary to that of civil society, providing funding, networking support or legal frameworks for the emergence and development of innovations [50,55]. This very function of the public sector is usually emphasized in local development studies [56,57].

Many SI initiatives establish multi-level governance mechanisms with public organizations that enable them to be effective and scalable. This reflects the interactive dynamic necessary for neo-endogenous rural development, combining bottom-up/top-down and endogenous/exogenous processes [23]. The interactive nature of SI led some authors to conceptualize bottom-linked governance or bottom-linked SI as novel forms of cooperative and democratic governance between civil society and public sector across different scales [58]. The concept is important to link SI initiatives with broader socio-political changes and to stress those processes enhanced by the public sector [59]. Bottom-linked governance can be an outcome of SI processes when social reconfigurations generate new combinations of actors, resources, functions and coordination instruments. Additionally, bottom-linked governance is key for SI durability because it facilitates flexible and inclusive spaces for new collective actions [59,60].

Nonetheless, the involvement of the public sector in SI and bottom-linked governance mechanisms is complex. Copus et al. [30] explain that this depends on the role that governments have historically played in each community, the prevailing welfare regime in the region or country, and the greater or lesser degree of decentralization existing in the prevailing forms of territorial governance. For example, recent research in Nordic rural areas identifies that the civil society–public sector pairing is the most relevant combination of actors in the early stages of SI and that the public sector is especially involved in SI initiatives related to the provision of social services [7]. Other authors note that the public sector should play a strategic role in revitalizing latent rural communities, as a source of inspiration and networking [46], in addition to contributing to improving territorial conditions for SI in those rural areas most weakened by their remote conditions and/or the impact of austerity policies [24,61]. However, there is also evidence—albeit limited—that the public sector can lead SI processes in rural territories, such as described by Franklin et al. [62] in the field of community food growing initiatives in Hungary.

While examining the role of the public sector in rural SI, allusions to the role of LEADER and Local Action Groups (LAGs) are also frequent. SI is one of the defining characteristics of the LEADER1 method since its implementation in the late 1990s [63,64,65], although it is not explicitly referred to until much later [66]. The capacity of the LEADER method to promote SI lies in the fact that its design pursues the formation of new cross-sectoral networks, bottom-up processes, public–private partnerships, and cooperation dynamics, which is directly linked to the emergence of new ideas and new social relations [67,68,69,70]. For instance, Dargan and Shucksmith [71], based on an extensive analysis of LEADER projects in different European rural contexts, concluded that the practical experience of rural development policies is mainly associated with the generation of local connections, collective learning processes and the improvement of the rural milieu [71]. Yet, other studies show that the practical implementation of LEADER does not always allow the full socially innovative potential of the method to be realized due the excessive bureaucratization, the tendency to prioritize low-risk projects and the existence of clientelist networks [72,73].