Geoscience faces dual recruiting challenges: a pending workforce shortage and a lack of diversity. Already suffering from low visibility, geoscience does not resemble the makeup of the general population in terms of either race/ethnicity or gender and is among the least diverse of all science, technology, engineering, and math fields in the U.S. Many studies discuss recruiting and diversity issues in science and math, but only a small number consider--and address quantitatively--barriers in geoscience. We interviewed 31 current and former geoscience majors (18 women, 13 men; 8 Hispanics, 21 whites) at a large university in the southwestern U.S. to collect 926 ''critical incidents,'' or experiences that affected choice of major. These critical incidents were classified, sorted, and analyzed by race/ethnicity and gender. We found that positive experiences in introductory courses, supportive family members, personal characteristics that meshed with geoscience, and outstanding field experiences were the most commonly reported factors influencing the choice of a geoscience major. Though our sample was not large, we interpret these factors as crucial tools for improving recruitment and retention. Hispanic students reported more familial factors, and more negative familial factors, than white students. Hispanic students also reported fewer informal outdoor experiences and fewer incidents involving personal factors. Men reported more critical incidents related to career and economic factors than women. Women reported more negative experiences than men in required nongeoscience courses. These findings suggest that sociocultural factors behind underrepresentation in other fields may similarly impede diversity in geoscience. Although geoscience majors share many common experiences, knowledge of subtle barriers that may exist for only Hispanic students and women in geoscience can inform recruiting, teaching, and advisement strategies.