Brazilians are a rapidly increasing Latino immigrant group in the United States (US), yet little research has examined factors influencing physical activity (PA) levels and behaviors of children growing up in Brazilian immigrant families. This information is needed to develop culturally sensitive interventions tailored to this population. Therefore, this qualitative study explored PA parenting practices used by Brazilian immigrant mothers living in the US. Thirty-seven Brazilian immigrant mothers with at least one child between the ages of 2 and 5 years participated in 1of 7 focus group discussions. Thematic analysis identified seven parenting practices that mothers employ that may encourage or facilitate physical activity their preschool-aged children's PA including: 1) modeling PA; 2) engaging and being physically active with child; 3) providing logistic support; 4) encouraging, praising, and offering motivational support; 5) watching, supervising, and teaching children how to engage in PA; 6) monitoring and setting limits to child's screen time; and 7) prompting child to be physically active. In addition, analysis identified four parenting practices that may discourage or inhibit children's PA including: 1) modeling of sedentary behaviors; 2) having rules and restrictions due to safety- and weather-related concerns; 3) limiting child's outdoor time due to parental time constraints; and 4) restricting child's outdoor and play time as punishment. Furthermore, analyses demonstrated that social contextual factors (e.g., income, housing, neighborhood safety, etc.) influence mothers' PA parenting practices and consequently, their children's PA. This is the first qualitative study, to our knowledge, to explore PA parenting practices of Brazilian-born immigrant mothers living in the US. Future research should further explore PA parenting practices of Brazilian immigrant parents including quantifying PA parenting practices that encourage and discourage PA, as well as examining the influence of fathers' PA parenting practices on young children's PA.