ABSTRACT The “Readiness Evaluation Tool for Oil Spills (RETOS™)” is an application upgraded in 2014 with the support of regional and international experts from industry and government, including associations such as Oil Spill Response (OSRL), the Regional Activity Centre / Regional Marine Pollution, Emergency, Information and Training Centre – Caribe (RAC/REMPEITC-Caribe), and the International Maritime Organization (IMO). The ARPEL Manual and RETOS™ provide a comprehensive set of criteria for industry and governments to assess their level of oil spill response (OSR) planning and readiness. The assessment criteria, agreed upon by the participating companies and institutions, provide the foundation for a series of checklists whereby gaps can be identified in spill response planning and readiness programs. The background for the tools is the “Assessment of Oil Spill Response Capabilities: A Proposed International Guide for Oil Spill Response Planning and Readiness Assessment”, developed for the 2008 International Oil Spill Conference. The RETOS™ Excel application and Manual list evaluation criteria according to the type of OSR program to be assessed. These tools have:Seven different scopes and two general perspectives (government and industry) are considered, including facilities, companies’ business lines, and government national programs.For each scope, there are three possible assessment levels for which OSR planning and readiness assessment criteria become increasingly more demanding.Each level contains criteria in 10 different categories (topic areas) and identifies critical criteria deemed necessary for completeness at a basic level.An additional category for institution-specific added criteria. Given that the criteria utilized relate to best international practices, RETOS™ represents a powerful tool for international benchmarking purposes. As of the end of 2016, workshops on how to use the tools have been presented in at least seven countries with over 400 total participants. RETOS™ has been used in more than 30 countries worldwide with most of those assessing national spill preparedness programs. Initial assessment results for Level A (basic) ranged from approximately 20% to 99% completion. Over 20 companies and institutions have utilized the tool with a similar range of results. Re-assessment provides a clear indication of progress toward higher levels of preparedness. The Manual and RETOS™ are currently available in English, Spanish, Portuguese and French and can be downloaded free of charge from the ARPEL web site (www.arpel.org).