Coined by Motorola in 1986 as a metric for measuring defects and improving quality, Six Sigma has evolved into a robust business improvement initiative. The success of Six Sigma deployment depends on a series of process/quality improvement projects undertaken by organizations. As learning and knowledge creation is vital to problem-solving environments, the primary objective of this thesis is to investigate the role of learning and knowledge creation on project performance and factors that impact them. The research addresses "Six Sigma-learning-performance" relationships through three related studies: (1) Develop a multilevel framework of Six Sigma linking organizational actions (macro), project execution (micro), and business performance (macro) (2) Identify the distinct learning behaviours exhibited by project teams and empirically investigate the impact of managerial factors (organizational and project level) on learning behaviours and in turn on project performance (3) Empirically examine how the motivational aspect of team and technical aspects of project execution interact to impact project performance through knowledge created (Goal theory and Sociotechnical systems theory perspective) The research adopts an explanatory sequential mixed- methods design, a survey followed by a multiple case study research (Quantitative Qualitative). In addition, the research observes the interaction between quantitative and qualitative research strands to achieve interpretive rigor. The quantitative data come from 324 members (project leaders and members) from 102 Six Sigma project teams and the qualitative data from five case projects from two European manufacturing organizations.Building on the existing literature which notes that Six Sigma supports learning and knowledge creation in teams, this research extends and helps refine our understanding of Six Sigma by explaining the mechanisms underlying the phenomenon and their antecedents and performance consequences. The thesis will be of interest to managers who are engaged in Six Sigma deployment and project leaders who lead process improvement teams. Researchers working in the field of Six Sigma will also benefit from this research.