Introduction: Our paper describes three examples of how public libraries in at-risk-neighbourhoods have worked with social innovations in order to develop and strengthen their services for minority groups. The libraries were chosen because they are frontrunners in the field of cultural diversity and social inclusion in Denmark. Method: The analysis relies first and foremost on data collected by the authors during the last decade. The methodological corroboration of the analysis is based on different elements of qualitative data such as interviews with staff, field observations, participation in workshops and evaluations of development projects in public libraries. Analysis: We examine different library services adopting theories of "Innovation Communities" and "Integrated Area Development", which both represent a locally based approach to conceptual development and social transformation. Results: Conceptual innovations in public libraries are introduced as three different approaches to creating innovative solutions of social problems and mobilizing ideas and resources for cultural and social transformations. Each of them describes a central innovation path and together they illustrate how manifold and different the particular conditions of library services to minority groups are and how slowly conceptual changes and innovation processes took place. As a main result, we present libraries in at-risk-communities as a cultural institution with a social responsibility and suggest a new concept entitled library-based community centres. Conclusion: It seems likely that minority groups in at-risk-communities gain substantially from library-based community centres if centres are based on social needs and the groups are prepared to participate in innovation processes. [This paper was published as part of: Proceedings of the Eighth International Conference on Conceptions of Library and Information Science, Copenhagen, Denmark, 19-22 August, 2013.]