This publication emphasizes the integrity and interdependence of various activities related to the bid invitation, technical and economic evaluation and contracting, it updates information included in the existing IAEA documents in order to better reflect the developments in the nuclear and energy industry, compiles a more compact and user friendly guidebook integrating the existing IAEA documents on the subject. It provides the necessary information to organize, guide and realize the activities related to the invitation, the technical and economic evaluation of bids, and contracting as an integrated process. Furthermore, this publication indicates how and to what degree the activities preceding the preparation of the bid invitation specification, the evaluation of bids and contracting could influence the process.