The path towards sustainability is closely related to new institutional and political paradigms and emerging models of practices, technologies, lifestyles, attitudes, and values. In this sense, the CIs, collectives where citizens self-organise through collaborative practices, networking, and knowledge transfer, come into their own, creating spaces for coexistence, reflection, and meeting where social innovation is the backbone. These multidisciplinary collaborative practices are developed on the basis of active citizen participation, improving individual and community life in the neighbourhood.
Today’s cities require a change in urban planning to address the complex relationships between citizens’ interests and needs, urban transformations, environmental degradation, urban policies, and economic interests in a sustainable approach 
. Social innovation is one of the pillars of sustainability that is becoming increasingly important as one of the dimensions that merit a multidisciplinary and transversal approach 
, where the active participation of citizens is required not only as recipients 
but also as co-creators of their reality. In this sense, a series of mechanisms and strategies have emerged that seek to involve citizens in decision-making processes in the city, such as participatory budgets, urban centres, living labs 
, and innovation centres, in which synergies are created between civil society, public administration, academia, and companies 
to seek solutions to social challenges; these strategies and platforms are usually guided by public administration. On the other hand, another type of participation and appropriation of space mechanism called Citizens’ Initiatives (CIs) are born in a spontaneous but conscientious way.
CIs can have different natures, guided through top-down processes or self-managed through bottom-up processes. This entry focuses on CIs aligned with bottom-up processes, which can be defined as “informal processes of citizen practice that resiliently and adaptively modify the urban environment. They are self-organized, collective practices that work for the urban empowerment of citizens and develop critical processes on the current city” 
These initiatives arise from a variety of problems and perspectives in the city, such as the recovery of public spaces, the creation of gardens, the use of renewable energies, and the protection of the city’s cultural and historical legacy, among others. As Cámara Menoyo pointed out, these are spontaneous processes with heterogeneous results, which, although they do not have a similar scope to the urban planning processes promoted by local authorities 
, have a positive impact on local problems and on raising citizens’ awareness.
The role of CIs in the transition to sustainability is a topic of growing interest 
due to recent evidence that they can in one way or another contribute to improving their environment and people’s quality of life, yet there is little evaluation and assessment of their level of contribution 
CIs have the potential to be less constrained by top-down structural processes and stimulate small-scale changes that positively impact the urban space and its citizens, as they are not subject to institutional policies and bureaucracies. That said, little is known about the potential of CIs to generate beneficial impacts for the Sustainable Development Goals (SDGs), as well as their leadership in creating fertile ground and contributing to a more sustainable urban city model 
2. Citizen Initiatives
The first widespread and organised collective movement arose as a reaction to excessive prices and poor-quality products, especially in the food sector. The modern cooperative movement emerged in Rochdale, in the northwest of England, in 1844, in the midst of industrialisation. Although the first cooperatives date back to an earlier period, at the hands of craftsmen, it was at this time that a wave of cooperative movements emerged, based on the principle of “self-help by the people” without distinguishing between consumers and producers 
The history of cooperative movements and community development initiatives are intertwined, as both movements have grown out of people’s need to collectively address issues affecting their daily lives. Cooperatives are an example of community-driven efforts to address economic and social inequality, while community development initiatives aim to promote social change by empowering communities to take charge of their own development. Both movements have been instrumental in addressing issues of poverty, access to goods and services, and social exclusion 
For instance, research has shown that cooperatives can have positive impacts on poverty reduction, food security, and women’s empowerment 
. Similarly, community development initiatives have been found to be effective in promoting community participation, social cohesion, and sustainable development 
Over the past 30 years, tools have been developed to support the development of these integrated initiatives for community change and provide visibility for them. In 1995, a team of experts from the University of Kansas created an online tool to guide community processes on their path to sustainability, called the Community Tool Box. This tool provides a range of content and information within the framework of community development and health, enabling the management and evaluation of community initiatives. Although this tool does not focus on assessing the environmental impact of initiatives, it helps communities overcome the barriers that may arise in their search for community development, creating consolidated groups that work together to generate solutions to common problems. As such, cooperative movements and community development initiatives can benefit from each other’s experiences and practices to further promote sustainable development and social change 
On the other hand, in Europe, the Treaty of Lisbon, which amends the Treaty of European Union (EU) and the Treaty establishing the European Community, which entered into force on 1 December 2009, opens a new window for citizen participation by giving citizens the opportunity to participate directly in legislative development 
. In the same vein, cohesion policy is the main investment instrument of the European Union 
, whose objective is to “support job creation, business competitiveness, economic growth, sustainable development and the improvement of the quality of life of citizens in all regions and cities of the EU” 
In 2020, the European Commission developed two pilot schemes to facilitate and enhance the active participation of citizens in social cohesion projects. In the first pilot scheme, the Organization for Economic Cooperation and Development (OECD) provided advice and training to the authorities managing the funds for the implementation of new initiatives to encourage citizen participation, in a coworking model where the needs and opinions of all the groups involved were considered. In the second pilot scheme, the European Commission earmarked EUR 250,000 to fund and support innovative CIs from small local civil society organizations. This favoured the inclusion of small and local civil society institutions in European funding programs, an action that generates citizens’ ownership of the changes brought about by the cohesion policies developed 
Simultaneously, in recent decades, CIs have emerged in Europe to address the many early 21st-century challenges facing society at the local level. Through them, citizens collectively strive to achieve common goals, based on the self-management of the participants. As a result, new collectives emerge and the associative fabric gains strength in the management of community needs, as well as in the improvement of their immediate environment 
In Spain in recent years, there has been a proliferation of such collectives and associations that empower citizens in the promotion and implementation of sustainable practices 
. In this type of association, citizens play an active role in the self-management of resources and in the generation of collective spaces for the debate of local problems, leading projects to reconfigure the physical and social context in which they are located 
. In this sense, several research studies attempt to analyse CIs, whether from the context 
, the typology 
, or the way they are managed 
The evaluation of these types of collectives and associations is scarce. The existing literature identified only three systems in Europe aiming at the measurement of the level of empowerment of citizens to modify and improve their environment. These are:
Towards European Sustainable Societies (TESS)—United Kingdom, Italy, Spain, Finland, and Romania (2013–2016).
Multidimensional assessment of the environmental and socioeconomic performance of community-based sustainability initiatives (MDA)—Italia (2019).
Criteria for assessing the transformation potential of sustainability initiatives (CATPSI)—Germany (2019).
An in-depth review analysing these three evaluation models can be found in 
. In summary:
In 2019, Celata and Sanna created an evaluation system assessing the impact of initiatives on their surroundings in four areas: environmental, social, economic, and community development. They evaluated 37 initiatives and classified them according to their typology: food cooperatives, solidarity shopping collectives, community gardens, community energy, recycling, and mobility initiatives 
In 2013, the European research project TESS (Towards European Social Sustainability) was launched, which analysed the role of community initiatives on the road to sustainability in cities, through the creation of an evaluation system and the subsequent analysis of 63 case studies, which made it possible to monitor and report on the social, political, economic, technological, and environmental impacts of community initiatives, as well as their savings in carbon emissions 
Finalmente, el proyecto Kriterien zur Bewertung des Transformationspotenzials von Nachhaltigkeitsinitiativen (criterios para evaluar el potencial de transformación de las iniciativas de sostenibilidad) desarrolló un sistema para evaluar el potencial de sostenibilidad y transformación de las iniciativas con el fin de revelar su valor y facilitar el reconocimiento y apoyo por parte de las administraciones públicas 
Los sistemas analizados comparten una estructura común compuesta por criterios, dimensiones, indicadores y un cuestionario. Sin embargo, difieren en la ponderación de parámetros, a saber, innovación, comunidades resilientes, recomendaciones a las administraciones, capacidad organizativa, escalabilidad, potencial de transformación y dimensión política. La evaluación de iniciativas en estos sistemas requiere mucho tiempo debido a la necesidad de entrevistas extensas que involucran hasta 130 preguntas muy específicas y extensas. En particular, si bien la sostenibilidad es un enfoque principal, estos sistemas no priorizan la mejora y transformación del espacio urbano.