This article argues that social norms are a major factor in determining the allocation of women's time and in regulating their economic activities. This view contradicts the assumption that time allocation depends on household economic level. Norms are gender specific and determine social penalties, such as verbal or physical abuse for women who have to travel to trade. In Burkina Faso social norms differ between the two ethnic groups: Mossi (more-conservative) and Bwa (less-patriarchical group). Results show that women from these groups react to changes differently. Women's labor include working on their husbands' fields, home and children, and on their own activities such as farming, selling, brewing, making Karite butter.