The award of public contracts has to comply with among others the principle proportionality. In many instances during the tender procedure the contracting authorities has to pay particular attention to the principle of proportionality. Think of the following topics: suitability requirements, requirements relating to financial and economic strength, requirements relating to technical and professional skill, selection criteria, requirements for consortiums and the award criteria.For many civil servants acting according to the principle of proportionality is an abstract concept that places them for difficulties when working on tender documents. The Dutch government is aware of this problem and offered a helping hand by having a special guide written solely on the principle of proportionality. This guide contains explanations, arguments and examples to help in the daily practice of all those working in tender situations: contracting authorities and economic operators. The Proportionality Guide is considered to be very helpful in the Dutch tender practice and it is for that reason the Dutch Institute of Construction Law took the initiative to translate the guide into English so it can be of use outside of the Netherlands as well.