It is obviously that SMEs play an important role in socio-economic development of each country. In Vietnam, SMEs account for 98 percent of the total enterprises that created 63 percent of employment and contributed to 45 percent of whole country GDP. However, SMEs have experienced a long- list- and- lasting weaknesses such as inadequate governance, lack of finance, low productivity, weak competitiveness…etc. To help develop SMEs sustainably, I have learned and applied quite a few tools such as Competency-based Economies through Formation of Enterprise (CEFE), Participatory Appraisal of Competitive Advantages (PACA), and Start and Improve Your Business (SIYB), etc. As there is one-size-fits-all solution, we need to be selective and mindful when apply one of these tools in to the practice. In terms of supporting community-based and natural resource-based SMEs, I applied the Market Analysis and Development introduced by Isabelle Lecup as well as Private Sector Engagement Strategy including market-based approach and Conservation Enterprise developed by USAID. I also initiated and promoted to apply the Public Private Community Partnership (PPCP) for scaling up viable business models under the recent USAID Green Annamites Program. In addition, I also worked as the Program Adviser to contribute to improving competitiveness of more than 1,800 SMEs in Ho Chi Minh, Daklak, Quang Nam, Hung Yen, An Giang and Hanoi, Vietnam under the SMEs Development Program co-funded by GIZ and MPI. We focused on (i) SME Policy/Enabling Environment; (ii) Local Economic Development; (iii) Competitiveness of Selected Sub-sectors/Value Chains; and (iv) Material Testing & Advanced Technical Services. After more than 20 years working in sustainable development field, including SMEs, I came up with Six critical successful factors to achieve sustainable SMEs. (see the Diagram)