Computational models can provide support in addressing challenges of urban planning. However, there exists a conflict between the required model inputs to reflect the decision problem, and the required insights into results for the decision maker to provide relevant inputs. This chapter presents how this conflict can be addressed by an interactive optimization approach. After introducing implied challenges, a general workflow is proposed, and its components are described in detail, namely (a) an optimization model, which incorporates decisions on multiple domains and scales, taken by different actors of urban planning, (b) the graphical representation of multivariate data allowing to explore results and define new inputs, and (c) a methodology to efficiently capture the large decision space of planners. These components are combined in the planning support tool URBio.