Racial/ethnic minority girls have a history of being underrepresented in STEM. Yet, there is a dearth of research that identifies the mathematics experiences that predict being on a STEM pipeline. Analyzing data from the Educational Longitudinal Study (ELS: 2002), we examined the relationship between mathematics attitudes, beliefs, and enrichment activities and being on a STEM pipeline among racial/ethnic minority girls. The findings indicated that for Black and Latinx girls, higher levels of mathematics self-efficacy beliefs were associated with being on a STEM pipeline. For American Indian/Alaska Native girls, endorsing a growth mindset was associated with being on a STEM pipeline. For Asian, Hawaii/Pacific Islander girls, mathematics enjoyment was associated with being on a STEM pipeline. Yet, endorsing higher levels of participation in mathematics enrichment activities and mathematics self-efficacy beliefs was associated with lower endorsements of being on a STEM pipeline for Black and American Indian/Alaska Native girls, respectively. Results build on previous work by highlighting important mathematics experiences that impact being on a STEM pipeline for racial/ethnic minority girls.