Six Sigma is a quality improvement approach renowned by its capability to analyze and synthesize problems in operational environments in order to get breakthrough improvements sustained over time. Six Sigma's strong logical positivism approach works as its most outstanding quality, and as its biggest weakness. Even though the highly detailed Six Sigma intervention process allows the analyst to propose in detail solutions to underlying problem causes, it fails to provide the analyst with a holistic perspective on how the proposed solutions may affect the overall system. Applied systems science on the other hand, provides the analyst with a set of methodologies that are adequate for different problem contexts but lacks the specificity found in Six Sigma Analysis. It is possible for the analyst to employ one (or more) of these methodologies as a guiding meta-methodology during a Six Sigma intervention process as a complementarist solution. In this paper we present a review of Flood and Jackson's Total Systems Intervention approach, and compare it with the Six Sigma problem solving methodology. The complementarist approach will produce a combined Systems Science-Six Sigma theoretical approach. The approach will be transformed into a theoretical framework capable of guiding Six Sigma interventions under a systemic approach in future work. Copyright, American Society for Engineering Management, 2011.