Due to the low income and rapid growth of the population, the government realized fully that the economic development of the country could not be safely delayed. Accordingly, Thailand inaugurated the First Six-Year National Economic Development Plan 1961. This study is dedicated to economic analysis and has examined the country's historical economic background as well as present-day economic development. The methods used to carry on the study are divided into six chapters. The first deals with the historical economic and political pattern for gaining some information about impediments to growth in the past. The second is concerned with population -- how the economic development was affected by various levels of population growth. The third to fifth chapters pertain to the analysis of economic performances during the first economic development plan with some recommendations about the direction of the future development of Thailand's economy. The final chapter attempts to examine and evaluate the achievement of the plan. The writer hopes that through this study interested individuals may get some insight into both the historical and present-day economic practices and problems in Thailand.