The main objectives of this research are (1) to study the mass media exposure behavior of the population in the rural-urban transitional area and (2) to study the functions of the mass media for its development, and (3) to test the relationship among these variables: modernity, mass media exposure, literacy, political participation, and economic status. The sample of this study was selected form resisdents of Amphoe Khlong Luang and Amphoe Thanyaburi, Pathumthani Province, totaling 903 households. The interview was performed through either the head of the household or his wife or his representative. The individual interview with questionnaires prepared by the researcher is the method of data collection. The data were collected during the months of March and April, 1980. From the hypothesis testing, the results turn out as follow: 1. The degree of mass media exposure depends upon modernity, literacy, occupations, political participation, and economic status. This hypothesis is confirmed. 2. Each mass mediumfunctions differently in the development task. This hypothesis is also confirmed. 3. In case the mass media do not function in the development task, other communication channels will replace their role. This hypothesis is confirmed. 4. There are no differences between the other communication channels and the mass media in their functions for the development task. This hypothesis is not confirmed. 5. Modernity, mass media exposure, literacy, political participation, and economic status are, to a high degree, positively correlated and these variables are mutally explanatory, if used jointly, to a high degree too. This hypothesis is not confirmed. According to the data collected from the survey, the researcher suggests a model for the modernity process of Khlong Luang-Thanyaburi. This model suggests that literacy has positive correlation with economic status and these variables also have positive correlation with the mass media exposure. Also, the mass media exposure has positive relationship with modernity. This model will be of great use to further study in Thailand.