Introduction; 1 Decision making in an architectural design process; 2 The Sjoelbak game: a decision-based design situation explained; 3 Decision-based design by means of the combination of sub-solutions; 4 A general phase model for the combination of sub-solutions; 5 Decision making in the combination process; 6 Management of the combination process; 7 A case study: Stedelijk Museum Amsterdam; 7.1 Project history; 7.2 Description of original single-input tool; 7.3 Description of multi-stakeholder tool; 8 The measurement and addition of stakeholder preferences; 8.1 Boolean and tri-valued veto preferences; 8.2 Multi-valued relative preferences; 8.3 Implementing a limited veto and relative preference system; 9 Conclusion; References