Revision with unchanged content. Organizations today are increasingly competing for market share, and in order to enhance their reach in today's markets, they need to maintain a low cost of quality, reduce waste, trim their production lines, and speed up manufacturing. Much of this can be achieved by implementing CI methodologies. The major CI initiatives available today are Six Sigma, Lean Production, TQM, Balanced Scorecard, Lean Sigma, and Reengineering. Not all CI methodologies are applicable to every organization: one may suit a particular organization better than others, and in what respects is not always clear, as no detailed research has been conducted in this area. This thesis therefore concentrates on describing and comparing CI methodologies. Modern CI trends are studied and a comprehensive study of the various CI methodologies that are available on the market is undertaken. This thesis is addressed to professionals and students interested in knowing more about Continuous Improvement. It is also addressed to individuals interested in continuing the research analysed in this thesis.