Graduate student teaching assistants from underrepresented groups may provide salient role models and enhanced instruction to minority students in STEM fields. We explore minority student-TA interactions in an important course in the sciences and STEM – introductory chemistry labs – at a large public university. The uncommon assignment method of students to TA instructors in these chemistry labs overcomes selection problems, and the small and active learning classroom setting with required attendance provides frequent interactions with the TA. We find evidence that underrepresented minority students are less likely to drop courses and are more likely to pass courses when assigned to minority TAs, but we do not find evidence of effects for grades and medium-term outcomes. The effects for the first-order outcomes are large with a decrease in the drop rate by 5.5 percentage points on a base of 6 percent, and an increase in the pass rate of 4.8 percentage points on a base of 93.6 percent. The findings are similar when we focus on Latinx student - Latinx TA interactions. The findings are robust to first-time vs. multiple enrollments in labs, specifications with different levels of fixed effects, limited choice of TA race, limited information of TAs, and low registration priority students. The findings have implications for debates over increasing diversity among PhD students in STEM fields because of spillovers to minority undergraduates.

来自代表性不足群体的研究生助教可以为 STEM 领域的少数民族学生提供突出的榜样和加强指导。我们在一所大型公立大学的科学和 STEM（入门化学实验室）的重要课程中探索少数民族学生与助教的互动。在这些化学实验室中，将学生分配给助教导师的不常见的分配方法克服了选择问题，并且需要出勤的小型主动学习教室设置提供了与助教的频繁互动。我们发现有证据表明，当分配给少数族裔助教时，代表性不足的少数族裔学生放弃课程的可能性较小，并且更有可能通过课程，但我们没有发现对成绩和中期成果有影响的证据。一阶成果影响较大，掉线率在6%的基数上下降5.5个百分点，通过率在93.6%的基数上上升4.8个百分点。当我们关注拉丁裔学生 - 拉丁裔助教互动时，结果是相似的。这些发现对于实验室中的首次注册与多次注册、具有不同水平固定效应的规范、助教种族的有限选择、助教的信息有限以及注册优先级低的学生都是稳健的。由于对少数族裔本科生的溢出效应，这些发现对关于 STEM 领域博士生多样性增加的辩论具有重要意义。当我们关注拉丁裔学生 - 拉丁裔助教互动时，结果是相似的。这些发现对于实验室中的首次注册与多次注册、具有不同水平固定效应的规范、助教种族的有限选择、助教的信息有限以及注册优先级低的学生都是稳健的。由于对少数族裔本科生的溢出效应，这些发现对关于 STEM 领域博士生多样性增加的辩论具有重要意义。当我们关注拉丁裔学生 - 拉丁裔助教互动时，结果是相似的。这些发现对于实验室中的首次注册与多次注册、具有不同水平固定效应的规范、助教种族的有限选择、助教的信息有限以及注册优先级低的学生都是稳健的。由于对少数族裔本科生的溢出效应，这些发现对关于 STEM 领域博士生多样性增加的辩论具有重要意义。