GO-GIRL! (Gaining Options: Girls Investigating Real Life!) is an intervention program that influences how girls experience math. At Roosevelt University (Illinois), a socioeconomically and ethnically diverse group of 7th grade girls met with graduate and undergraduate students for 10 Saturdays, forming small research teams of girls and student mentors. The teams designed an inquiry plan with peer pressure as the topic and worked through the scientific method to develop, test, and evaluate hypotheses based on survey data.