This thesis is concerned with the development and evaluation of an integrated model combining Six Sigma and Knowledge Management (KM) concepts. The model is intended as a methodology to support the applications in SMEs. SMEs have limitations when employing the Six Sigma programme due to the limited time, cost and effort, and other barriers from SME characteristics (e.g. organisation culture, structure and strategies). Therefore, SMEs need a methodology to guide and facilitate the implementation of Six Sigma. KM is an issue that is of interests to management; however, the applications are still limited in SMEs. Hence, KM is another core issue integrated into the model to guide people through Six Sigma and to manage the large amount of knowledge generated by Six Sigma activities. To facilitate the implementation in SMEs, three key aspects (avoiding complicated system, solving cost constrains and avoiding extra time and loads) are considered as the key approaches when designing the system. There are some key features within the system designed; being a knowledge hub for learning about Six Sigma and supporting issues; providing simple explanations; giving simple and lean approaches and steps to implement Six Sigma; adopting internal training or self-learning systems; highlighting the relationships between Six Sigma and other regular operations (e.g., using process maps, performance measures and habitual problems to indicate the Six Sigma project and monitor the results). Five KM approaches are introduced to the system; process-based knowledge map, searchable project library, expert locator and expert search, performance data collection and Six Sigma knowledge source. These conceptual designs of the methodology have been developed into software as a PC-based system. This software uses web-enabled technology as the platform for running the system. The software enables users to have a choice of running the system as a PC-stand alone system, Internet or Intranet. The elements of the system can be separated into three sections; Six Sigma content and development issues, supporting issues. and KM approaches. The first section gives an overview of Six Sigma and also supports "gearing up and adapting Six Sigma to an organisation". The second section considers some supporting issues (e.g. performance measures. process map and habitual problems) used for facilitating the Six Sigma activities. In the final section. five KM approaches mentioned above are developed. An exploratory study (in-depth survey) with 34 organisations in Thailand is presented. The result from the content analysis of the respondents revealed some key aspects; firstly, SMEs have only little knowledge of Six Sigma and KM, secondly, respondents want to have the methodology or software helping them to approach these two issues and finally, respondents are satisfied with the efficiency and functionality of the software developed. This research in general has supplied arguments that Six Sigma and KM can be developed and implemented in SMEs. The software can guide SMEs and be the supporting material to implement both Six Sigma and KM. Research findings also reveal several implications, which practitioners can undertake to facilitate or improve the operations of an organisation.