Supplemental Material for When and Why Working Together Benefits First-Generation College Students: A Registered Report

Participants were 209 students enrolled in a large undergraduate course at a West Coast public university in the United States.Of the 209 students, 177 took an extra credit survey (in which they reported demographics) at the end of the academic term.Thus, we only have selfreported demographic information for 177 students.However, we obtained objective firstgeneration college student status for 194 students from the university registrar.We used selfreported FG college student status from the self-report survey for 13 students who did not have registrar data.Thus, we have complete data for all of our primary variables of interest (reported in the main manuscript) for 207 students.The two students who did not have data for FG student status were excluded from analysis.We asked participants about their gender identity with the item "My gender is" and the answer options were "Female", "Male", and "Other".From the 177 students who took the extra credit survey, 35 identified as male, 141 identified as female, and 1 person identified as "other."Students reported being between the ages of 18 to 47 (M = 21.01,SD = 3.03).154 students selfreported having entirely or mostly been raised in the United States.Participants were asked about their racial or ethnic group they belong to with the item: "Please check all racial or ethnic groups that you belong" and the answer options were "African-American, Black, African, or Caribbean", "Asian-American, Asian, or Pacific Islander", "European-American, White, Anglo, or Caucasian", "Hispanic-American, Latino(a), or Chicano(a)", "Native-American or American Indian", and "Other (please specify):___".67 students identified as East Asian/Asian American, 5 as African American, 61 as Latino/a, 21 as Non-Hispanic White, 4 as other and 19 as having more than one ethnicity.Taken together, 44% of the sample was classified as coming from an underrepresented minority background (URM).For analyses including race/ethnicity and other