The goal of this article is to identify and understand the relationship between critical success factors for Six Sigma programs and its projects performance, considering Six Sigma projects. This article explores those relationships through PLS (Partial Least Squares) method, using a sample of 149 respondents in Brazil and Argentina. The variables were collected initially by a survey conducted with Black Belts, Green Belts, program managers and company executives and goes further on projects documental analysis. The results show that not all the claimed critical success factors are relevant for program or project performance, what could direct the effort of companies into working harder in the relevant ones. This study has a noteworthy contribution to Six Sigma literature presenting a structural model that shows the significant impact of Six Sigma Method, Project Management and the Project Manager competencies on project performance.