The purpose of this research was to explore the operating conditions of Small and Medium-sized Enterprises (SMEs) and their effects on the rating of products in Thailand’s One Tambon One Product (OTOP) program. The sample group in the research was the 330 owners or executives of Small and Medium-sized Enterprises that produced for the OTOP program and their products were rated 3-5 stars. A questionnaire was used to collect data. The statistics used for data analysis were Percentage, Mean, Standard Deviation. Chi-Square, and one-way ANOVA, while Scheffe Analysis was used for multiple comparisons. The study found there were 19 operating conditions of the SME producers of OTOP program found affecting the rating of their 3-5 star products including; Marketing Operating Conditions - such as packaging, main target market, marketing promotion, Production Operating Conditions - such as production policy, production plan, standard certifications, raw material management, production methods, product development, member selection, production cost, Financial Operating Conditions - such as initial investment, working capital, working capital management model, main operational objectives, operational strategy, assignment of duties and responsibilities, employee performance indicators, and the member remuneration, which were all found statistically significant at the .05 level.