Responsive cities define the future of urbanization. They evolve from smart cities, with a fundamental difference: The citizens move from the center of attention to the center of action. Responsive citizens use smart technology to contribute to planning, design and management of their cities. To demonstrate the potential of Responsive Cities, this course will define the concept of Citizen Design Science, a combination of Citizen Design, Citizen Science and Design Science. Experts, citizens and scientists participate in Citizen Design Science. This approach is still in an early stage of development, but with the Responsive Cities Massive Open Online Course, you will be ahead in exploring and defining its possibilities. ‘Responsive cities’ is the fourth edition of the ‘Future Cities’ series on urban MOOCs. The ‘Future Cities’ series is the first and complete series of urban courses dealing with the design, management and transformation of cities for their sustainable and resilient future. With every edition, the series becomes more interactive. It increasingly empowers citizens around the world to become part of the development of their own cities, especially in those places where this knowledge is needed most. Therefore, the course is inclusive for every individual interested in the planning, construction, redevelopment and management of future cities. The course is open to anyone regardless of background, skills, knowledge, or age.