Citizen science, particularly in the social sciences (citizen social science), has gained significant traction in recent years. This field encompasses various approaches to citizen participation, ranging from data collection to full co-creation of research projects. Two main perspectives exist: one focused on democratizing science and empowering grassroots research, and another employing a more top-down, scientist-led approach. The paper highlights the increasing importance of incorporating citizens' social concerns and emphasizing varying levels of participation. It argues for a more explicit methodological conceptualization of communicative spaces in co-creational citizen social science projects, focusing on the exchange and reflection between project partners regarding research design, ethics, and practical effects on co-researchers. The authors propose the 'research forum' as a methodological framework to address this need, emphasizing its role in fostering co-creation and co-design across all research phases.

The paper reviews existing literature on citizen science and its evolution, particularly the rise of citizen social science. It discusses different models of participation, ranging from contributory to collaborative and co-created projects, even going further to include citizen-led initiatives. The authors also engage with concepts like knowledge coalitions, socially robust knowledge, and transdisciplinarity, emphasizing the importance of integrating lifeworld knowledge into science and vice-versa. The review touches upon the communicative and discursive turn in social and political science, highlighting its relevance to a framework for co-researcher communication. Key thinkers mentioned include Habermas, Kemmis, and McTaggart, whose work on communicative action and participatory action research informs the proposed methodology.

The core methodology centers on the 'research forum,' conceptualized as a series of workshops designed to foster co-creation throughout the research process. This forum acts as a horizontal, inclusive, and safe space for communication among project partners (academic researchers and co-researchers). The authors detail its modular structure, adaptable to project needs in terms of frequency, focus, format, and length. Rules of communication are emphasized as an ethical foundation for equal exchange. The researchers’ role as moderators and facilitators is highlighted, ensuring an inclusive and safe environment. The forum's structure aligns with research phases: (1) defining research topics through a 'knowledge coalition'; (2) conducting research through discussions, data collection, and analysis; and (3) a concluding discussion, including process evaluation and feedback. The methodology connects to four key aspects of citizen social science: participation (co-creation and co-design), transdisciplinarity (diverse stakeholder involvement), reflexivity (addressing power relations), and impact (achieving relevant research outcomes). The authors further elaborate on these aspects, distinguishing between different models of participation and defining transdisciplinarity's role in integrating various perspectives. Reflexivity is viewed as crucial for addressing power imbalances within the research process. The importance of the research's social and political impact is stressed, emphasizing the creation of practice-situated and socially robust knowledge.

The paper presents a case study involving a co-created research project with three multigenerational co-housing projects. Eighteen research forum sessions were conducted over a year, engaging 50 co-housing residents directly and 160 indirectly. The sessions employed diverse, low-threshold methods such as posters, photos, role-playing, and biographical interviews to encourage participation from various age groups. The authors identify four key dimensions of co-researcher communication emerging from this case study: 1. **Opening up spaces for social encounters:** This involved creating a safe space built on trust and mutual respect, addressing emotional, task, and organizational issues through strategies like check-in rounds and equitable task distribution. The researchers also facilitated a shift from everyday interpretations to a more distanced, reflexive mode of inquiry. 2. **Establishing communicative practices:** This focused on fostering a culture of dialogue and shared understanding, addressing potential power imbalances through careful moderation and transparent communication. Strategies included ensuring turn-taking, mediating conflicts, and making research materials widely accessible. 3. **Initiating a process of social self-understanding:** This involved guiding participants toward shared interpretations of their reality, using scientific methods to transcend individual perspectives and reach generalizable findings. The process was viewed as a form of mutual translation between subjective experiences and shared understanding of community practices. 4. **Engaging in (counter-)public discourses:** This involved using research findings to influence social and political discourse beyond the immediate co-housing communities. The co-housing projects used their collective voice to advocate for policy changes related to affordable and sustainable housing, demonstrating the potential for citizen social science to drive social transformation. The authors discuss how the knowledge generated within the research forum translated into both internal community-building actions and external political engagement.

The findings demonstrate the effectiveness of the research forum as a methodological framework for co-creation in citizen social science. The four dimensions of co-researcher communication—opening spaces, establishing practices, fostering self-understanding, and engaging in public discourse—show how the forum facilitates participatory research, transdisciplinary knowledge production, reflexive engagement, and meaningful social impact. The case study illustrates how co-researchers' perspectives are central throughout the research process, leading to both scientific and social/political outcomes. The discussion underscores the potential of citizen social science to bridge the gap between academic research and real-world social concerns.

The research forum offers a valuable methodological approach for co-creation in citizen social science, promoting democratic participation and generating socially robust knowledge. It facilitates meaningful engagement of co-researchers, leading to both scientific advancements and tangible social and political change. Future research could explore the applicability of the research forum in diverse contexts and investigate its potential for addressing power dynamics more effectively.

The study's focus on multigenerational co-housing projects may limit the generalizability of findings to other social contexts. The relatively homogenous social background of the co-researchers might also influence the results. While the researchers implemented strategies to mitigate power imbalances, it is acknowledged that complete neutrality is difficult to achieve in participatory research. The success of the forum may depend on the active participation of co-researchers, with challenges faced in fully incorporating those who did not attend the sessions.