Successful women role models can be-but are not always-effective in increasing pursuit of science, technology, engineering, and mathematics (STEM) careers among girls. What makes a woman role model motivating for young girls? An experimental study (N = 205 girls aged 5-8 years; 42.0% girls of color) investigated the effects of a role model's messages about her own ability and interest. The model portrayed her ability and interest as quantities that developed over time (a growth mindset) or that had always been present (a fixed mindset). The role model's growth (vs. fixed) mindset messages about ability-but not interest-increased girls' interest and self-efficacy in the scientist's field, but these effects were observed only among girls of color (ds = 0.56 and 0.65 for interest and self-efficacy, respectively). The findings contribute to theory on role models and growth mindsets, and they also have implications for the design of effective role model interventions.