Well architecture advances from conventional wells to horizontal Then multilateral wells, which have maximized reservoir contact, have been paralleled by advances in completion-equipment devel-opment. Passive inflow-control devices (ICDs) and active interval-control valves (ICVs) provide a range of fluid-flow control options that can enhance the reservoir sweep efficiency and increase reserves. ICVs were used originally for controlled, commingled production from multiple reservoirs, while ICDs were developed to counteract the horizontal well's heel/toe effect. The variety of their applications has proliferated since these beginnings. Theii application areas now overlap, resulting in it becoming a complex, time-consuming process to select between ICVs or ICDs for a particular well's completion. This publication summarizes the results of a comprehensive, comparative study of the functionality and applicability of the two technologies. It maps out a workflow of the selection process on the basis of the thorough analysis of the ICD and ICV advantages in major reservoir, production, operation, and economic areas. It provides detailed analysis of • Reservoir-engineering aspects, such as uncertainty management, formation heterogeneity, and the level of flexibility required by the development • Production and completion characteristics, such as tubing size, the number of separately controllable zones, the completion of multiple laterals, and the value of real-time information • Operational and economical aspects, such as proper modeling, gas- and oilfield applications, equipment costs and installation risks, long-term reliability, and technical performance. The results of this work's systematic approach form the basis of a screening tool to identify the most appropriate control technology for a wide range of situations. This selection framework can be applied by both production technologists and reservoir engineers when choosing between passive or active flow control in advanced wells. The value of these guidelines is illustrated by their application to synthetic- and real-field case studies. Copyright © 2010 Society of Petroleum Engineers.