It is important for a contracting authority to ensure that it will enter into a contract with an economic operator that has the ability to perform and complete the contract. Selection of economic operators means the process of assessing and deciding which economic operators are qualified to participate in the tendering procedure. This process must be carried out by applying objective, non-discriminatory and transparent selection criteria, which are set by the contracting authority in advance and disclosed to economic operators. SIGMA Brief 7 gives an overview about the relevant rules of Public Procurement Directives which significantly limit a contracting authority’s discretion in this area. It also provides a checklist of the main points that should be addressed when defining the overall strategy for the selection of economic operators.