For two decades now, executives have witnessed an explosion of management tools, ranging from Knowledge Management to Strategic Alliances. That burst was fueled by their need to successfully navigate an increasingly competitive marketplace. To help inform managers about the tools available to them, in 1993 Bain & Company launched a multiyear research project to gather facts about the use and performance of management tools. Every year or two since, we've interviewed senior managers and conducted research to identify 25 of the most popular and pertinent management tools. Our efforts to understand the continually evolving management tools landscape have led us to add five tools to this year's guide-Consumer Ethnography, Corporate Blogs, Lean Operations, Mergers and Acquisitions and Shared Service Centers. While none is new, per se, each tool is growing in use and playing an increasingly important role in today's business world.