This paper looks at the existing toolsand approaches most commonly used in developed anddeveloping countries to review the stock of regulations. Thetools reviewed can generate benefits in the short term, butthey are most effective as part of a longer-term sustainedinitiative. This paper has a particular focus on thechallenges that arise from their use in emerging anddeveloping countries. The objectives of this paper include:1) explaining the rationale for the use of these tools andapproaches; 2) discussing each one of them in a succinctway; 3) considering the extent to which these tools cansupport more systemic regulatory reforms in the medium andlong terms; and 4) considering the particular challenges andopportunities regarding their use in developing and emergingeconomies. Section one is a brief description of therationale and context for applying tools and approaches toreview the stock of regulation. It includes a reference tobenefits and preconditions to make use of these tools. Italso presents a categorization of the most commonly usedtools and a comparative table on the way these tools can beapplied. Section two presents a description of each of thedifferent tools and approaches available, and discusses theway they are used and their main components. It includesreferences to international experiences in which these toolshave been integrated into the regulatory reform process.Section three presents preliminary commentary about some ofthe potential advantages, disadvantages, and impacts ofusing these tools and approaches in developing countries.Some particular cases are presented to illustrate thesetrends. The section also includes a short description of thesequence observed in the use of some of these tools.Moreover, this section illustrates how these tools can (orcannot) generate gains in the short term and also provide abasis for further and broader regulatory reform programs.