This article analyzes how and where women participated in Brazilian commerce between 1869 and 1904. Over half of Rio de Janeiro's female population worked at the twentieth century's turn, but very little is known about women in commerce. Evidence from formal business partnership contracts demonstrates that women comprised a significant and dynamic sector of the merchant community, despite legal and social barriers. More importantly, their business habits largely paralleled those of their male counterparts. These findings break from current scholarship that narrowly defines businesswomen as exceptional. An analysis of female economic activity, along with the institutional structures regulating their market participation, suggests that gender shaped women's entrance into the market but only narrowly affected their pursuits. Recognizing the various ways that women considered the legal and social demands of their civil status with the broader demands of the market offers a more complete portrait of female economic activity during one of Brazil's most impressive eras of expansion.