The author describes economic factors, including farmland, socio-economic status, education, advice on family planning, Thai language ability, number of dead births, and birth control to find out which factors were related to number of live births and desirable number of children or fertility of Yao women. The sample group consisted of 528 participants aged between 15 and 49 years old and residing in Lampang Province. The study findings revealed that the economic factors and number of live births were not related to fertility. Moreover, Thai language ability and birth control were negatively related to fertility, but number of dead births was positively related to fertility. Advice on family planning was negatively related to a desirable number of children. For birth control, it was found that Yao women, regardless of age groups, did not practice birth control until they had had five children or more (pp. 72-76).