This study examines the direct effect of economic and social conditions on the ideal number of children of females who were just married and residing in the “population awareness areas” of Kanchanaburi Province. According to the review of primary data of Kanchanaburi Demographic Surveillance System in Kanchanaburi Province, round 2, 2001, from a sample group of 242 females aged 15-29, with a period of marriage of not exceeding 3 years, it was found that the educational levels of females, which were divided into 3 groups including “primary education”, “secondary education”, and “higher education”, had an impact on their desires to have only one child; meanwhile, when considering factors which had an impact of females’ desires to have two children at a replacement level in terms of females’ incomes, it was found that there were no significant differences of females’ desires to have two children; on the other hand, females who completed higher education and potentially desired to have two children were in a larger proportion than those who completed primary education. When considering factors which had an impact on females’ desires to have the ideal number of children more than three children, it was found that almost all economic and social factors had a negative impact. In particular, the “income” factor had an insignificant impact. Meanwhile, when considering the educational factor, it was found that females did not desire to have the ideal number of children more than three children with statistical significance. It was obvious that factors determined the ideal number of children of just-married females including the economic and social conditions of females such as educational levels and occupations. Therefore, studies of fertility of just-married females of reproductive age should emphasize the importance of educational levels and occupations of females.