Regulatory impact analysis (RIA) is a systemic approach to critically assessing the positive and negative effects of proposed and existing regulations and non-regulatory alternatives. This publication brings together recent OECD research and analysis concerning methodological issues and country experiences with RIA. The collected papers cover a number of challenges to the effectiveness of RIA including: systemic factors which influence the quality of RIA; methodological frameworks that can assist RIA to improve regulation; guidance on using RIA to avoid unnecessary regulation of competitive markets; and a review of the use of RIA in the regulation of corporate governance across a number of OECD countries. Taken together, this publication provides valuable, practical guidance on how to improve the performance of RIA systems to promote economic welfare through better quality regulation.