Within the context of national and international developments in Citizen Science and Open Science and with regard to TU Delft's development of several citizen science projects and the growing expertise in working with citizens, we explored the initiatives and organisations active in Citizen Science, its implications in research and education and its positioning within the Open Science framework. In co-creation with researchers and stakeholders from Delft and inspired by the 10 principles of Citizen Science from European Citizen Science Association (ECSA), we propose a definition of citizen science and a vision for citizen science at TU Delft. We conclude that the involvement of citizens in the scientific research process requires a specific approach and a specific set of skills. We argue that cooperating with citizens in scientific research projects, while using scientifically sound methods and using specialised skills, increases mutual understanding and can aid in collecting hard-to-access or long-term data, with benefits for both the university and citizens. We identified researchers’ needs of sharing experience, of learning how to work with citizens and a general need for the support and resources required for new types of activities and skills specific to Citizen Science. Additionally, we brought out concerns related to trust and data reliability issues when working with citizens. It is crucial for the research with an active citizens' role to be designed in accordance to the principles of Open Science so that it meets the requirements of transparent high-quality scientific practice. Based on all the findings, we determined that citizen science confers a new dimension to Open Science. We make recommendations for the next steps in supporting an emerging community of citizen scientists in our university.